"Oga" redirects here. For other uses, see Oga (disambiguation).
|Alias||The Rampaging Ogre|
Fuck (ファック, Fakku)
The BoB Brawler
Child Rearing Badass
|Age||16, 18 (2 years later)|
|Birthday||August 31 (?)|
|Horoscope||Virgo  (in 1992)|
|Height||179 cm (5'10.5")|
|Base of Operations||Ishiyama High School|
|Previous Base of Operations||Saint Ishiyama Academy|
|Relatives||Youjirou Oga (father) |
Shouko Oga (mother)
Misaki Oga (sister)
Beelzebub IV (adoptive son)
Nico (adoptive daughter)
Mashaharu (great uncle)
|Anime Debut||Episode 1|
|Manga Debut||Chapter 1|
|Seiyū||Katsuyuki Konishi (Japanese)
[Andrew M. Gray] (English)
Tatsumi Oga (男鹿 辰巳, Oga Tatsumi) is the main male protagonist of the series Beelzebub and he's a first-year student at Ishiyama High School.
He's the adoptive father of the Demons, Beelzebub IV, and his younger sister, Nico. Early on, he attempted to pass Beel off to others on numerous occasions since unknowingly forming a contract with him.
Oga's usually seen sporting a grotesque grin and displays demonic features when he's either angry or disturbed. He has brown hair and sharp black eyes, he's rather muscular with a widespread build, and his attire usually consists of a worn-out shirt, a brown leather jacket, and plain pants (usually jeans).
He's been shown on a few occasions to be wearing either sweatpants, and on one occasion, he's even been shown wearing his pj's (ironically detailed with pinstripes going down the side). When Oga attempts to smile, he is usually seen with a demonic, evil grin. This speaks to his lack of social skills (due to his inhibition in a juvenile delinquent high school).
When fighting, Oga appears to have a different look. Aside from his rare comedic entrances (usually as a relief from an intense situation), he is usually very calm and actually quite aware. His eyes are alert and he seems in control of his emotions. However, Beel doesn't transfer this emotion, and he's usually shown in a maintained and alert state.
When he uses Super Milk Time, he becomes one with Baby Beel. His hair is green and he's sucking the pacifier Baby Beel uses. He's the same height that he's in his original state, and wears the same clothes.
Initially, Oga was nothing more than a crude and uncaring delinquent whose only friend seemed to be Furuichi. While he wouldn't start fights, he would take deliberate pleasure in inflicting the most pain possible when facing his opponents, regularly resulting to cruel and unusual methods of punishment for his defeated enemies, showing a high amount of sadism. It is because of these qualities that he was initially chosen to become Beel's parent.
Alaindelon described the ideal parent of a Demon Lord as being "strong, tough, self-centered, and cares nothing for his fellow man". These traits sum up most of Oga's personality. As the series continues, it should be noted that the trials Oga has faced and the new friends he has gained have somewhat altered his personality. For example, when the Rokkisei called out Ishiyama to meet them on the rooftop, he initially came alone. But later on, when Himekawa, Kunieda, and Natsume arrived, Oga smiled, knowing that they have his back. Though he retains his love for his cruelty, he is now much calmer and easier to be around than he was at the start of the series.
Still, in his own twisted, roundabout way, he seems to care for the people that are close to him. When Furuichi was gone during the summer vacation and left Oga alone, he called Alaindelon to transport Furuichi back home just so he could hang out with him. He also beat up and embarrassed Miki back in middle school, though he did it to protect him from Kiriya Reiji. Since he knew that both Miki and Kiriya would move to Nara at the same time, Kiriya would've attacked Miki in Nara where Oga wouldn't be there to protect him. When Hilda and Beel went missing and his sister Misaki threw him out of the house, promising to not let him back in unless he brought them back, Oga acted as if he didn't care. Instead, he complained about the heat to Furuichi and decided that they should go down to the river. Furuichi realized that the river was where Oga had first met Beel, also realizing that Oga meant to look for them after all.
Oga doesn't seem to have any sense of appeal for or opposition against girls, unlike Furuichi, who is easily seduced and will not hesitate to pick up girls. However, he does also have a sense of chivalry, as said by Hilda, as Oga will not fight or harm a woman. This was proven true when he only dodges during his fight with Aoi, and more recently when fighting the female Pillars he held back when he realized he was about to hit a girl. The only times he actually hits a girl was during a sparring match with Aoi to determine if they were capable of learning Black Techs, and knocking out Yuchelle by destroying her weapon. It is also hinted that he disapproves of underage smoking and drinking.
As much as Oga hates it, he tends to listen to lectures very well. For example, when Oga was telling Teimō about Baby Beel's demon praying dance, Kunieda quickly takes him to the side and lectures him about being selective about who to talk to about Demons, and to only talk about them to those who are involved. After that, Oga never told anyone besides Furuichi, Kunieda, Ittōsai, and Saotome, save for other demons. Another example of Oga paying attention is when Saotome was lecturing him about using Super Milk Time for no more than 5 minutes. When he uses Super Milk Time later, he only ended up fighting for 5 minutes after using a huge blast that knocked him unconscious.
As the series progresses, Oga learns how to put his pride aside and knows when to follow orders. An example was when Saotome said that the Ishiyama students were going to need training with him. All of the delinquents didn't want to train with him because they thought he was an "old geezer", and that he was weaker than them and it would damage their pride. Oga was the only one who stepped up and agreed to train; instead of being arrogant, he listened to reason and sought to become stronger.
Oga still believed in Santa Claus during his toddler years. One Christmas, he waited all night with a camera by the front door hoping to see Santa Claus. He eventually developed a fever afterward. Later, he dreamt of seeing the old man with a red loincloth across the river, and apparently swam toward him to get presents while the old man was telling him not to come yet; apparently, the old man was his deceased grandfather and Oga actually had a near-death experience. Oga eventually learned that Santa Claus was not real when he was three years old. Moreover, for every Christmas until the sixth grade, Oga would receive mechanical pencils.
During the fifth grade, Oga headed to see his older sister but was approached by a classmate, Takayuki Furuichi, both of whom were in Class 5-3. Upon being asked whether they can walk home together, Oga simply told the boy to not stand behind him and continued on his way.
When in the city, he realized that Furuichi was still behind him and became annoyed. Being unable to correctly pronounce his name, Oga inadvertently insulted him. Oga also told Furuichi to put "it" away, while also warning him about the dangers of the city. However, after the boy relented on staying with him, Oga decided to let him stay anyway. However, he did warn Furuichi not to stand behind him.
The two boys went to the arcade where the Red Tail were at. Oga went to meet his older sister and dropped off a magazine for her, only to be subsequently beaten through kicks for being late. Once the beating was over, Oga told Furuichi why he should not stand behind him and prepared to leave; however, Furuichi insisted on staying because of the girls, prompting Oga to call him weird. Oga's intentions to leave were then put aside after he learned that the girls are going to a party, which he excitedly wanted to attend. He and Furuichi both ended up joining the Red Tail to the party.
However, the party was revealed to be a simply brawl between the Red Tail and a biker gang from Donbura High School; despite so, Oga remained interested in the party and even partook in the beatings against the older boys. Throughout the fights, he protected Furuichi from the delinquents and even warned the boy not to stand in the back, otherwise it would be hard to protect him. Nevertheless, Oga goes out on a rampage and grinned evilly while having fun.
During school, he was asked by Furuichi whether he always got into fights, which Oga stated he only does when called out to it. A group of boys then asked Furuichi to play dodgeball with them. Oga convinced Furuichi to go and added that he doesn't want to; however, while the boys were all having fun on the playground, Oga watched them from inside his classroom.
Oga later headed home during the afternoon once school had ended. On the way, he was approached by Furuichi, who asked whether he was going to have another fight. Surprised by the question, Oga asked whether he had an issue about it. He was then told that Furuichi will be his opponent; uninterested, he started walking away and added that he should not have to fight Furuichi.
However, they ended up getting into a brawl anyway, after Furuichi stated that he would be the winner by default and that he would tell their classmates how Oga used a girl's bathroom. After beating up Furuichi, Oga became surprised by the young boy's endurance despite his genuine weakness. Afterward, Furuichi told Oga that he wanted to be his friend, prompting Oga to smack him on the back of the head. Oga revealed to Furuichi that all of the friends that he did have ended up dragging him down and later leaving him; upon saying this, he reflected on the dark comments that he heard from their classmates in the past. He then picked up his backpack and started leaving, telling Furuichi that he cannot concentrate on his own battles when his "friends" need his protection. However, he then noticed Furuichi rise up and walk beside him, saying that he will stand beside Oga instead. This comment leaves Oga surprised but he ends up laughing out of happiness; happy, he let Furuichi go with him. As they go on their way, Oga mentioned that they will be fighting someone strong and was surprised to hear that Furuichi would hide once they meet him.
One day, Oga and Furuichi went out "pokopenning" everything behind their school; they continued to "pokopen" things while heading home. On their way, they were approached by a woman who asked whether they know about "pokopen"; thinking of it as a secret word that they came up with, Oga became suspicious. The two boys then watched as the woman left and stated that she was also a "pokopen". This incident would later be remembered as "The First Pokopen Incident".
Tōhōshinki ArcOga is defeating armed mercenaries and local thugs. As they pleaded for mercy, and with an off-screen tilt, he was shown to have battled them rigorously. Many were unconscious, and although it seemed the series was unfolding in an event-themed fashion, it was shown that it was really Oga's retelling of what transpired to Furuichi Takayuki. His story continued and he explained how a large man (Alaindelon) came floating upstream (the local riverside), and how he cracked open, revealing a small baby inside. Furuichi is shocked by Oga's lack of storytelling abilities (although the retelling was later revealed to be true), and the two continue in loud voices. Beel is completely focused on the conversation at hand, and he remained quiet through most of their conversation. Oga continues to rant about the Beel situation, revealing that he must take care of the demon baby because the child is so attached to his raw abilities. He mentions Hilda during his conversation and Furuichi is quite taken by her.
The next day, Oga takes Beel to school with him. Furuichi wonders out loud why he would go through that much trouble for the kid. The story continues with Hajime Kanzaki's mercenary forces coming in contact with Oga. Furuichi is worried about Oga's status among the students at Ishiyama High. The students are convinced Oga is the father of Beel and are shocked by their self-prescribed qualifications. Oga becomes aware of Hajime Kanzaki's status as among the four Tohoshinki. Being the somewhat sadistic and irresponsible teen that he is, Oga seeks out Kanzaki in an attempt to force Beel on him. His logic was that "strong men" were most appealing to Beel, and that the most malicious of characters would satisfy his needs. When the two meet, the discussion takes a dangerous turn as Kanzaki sends one of his own men flying with a direct attack (after annoying him). Beel was touched on the head by Kanzaki. Oga realized that Kanzaki was rejected as Beel did not react, and in retaliation, sent Kanzaki flying. Leaving Kanzaki's men completely shocked, Oga leaves the area feeling rather disappointed.
The next step for Oga was handling the other menacing forces of Ishiyama. The second step was Tatsuya Himekawa, another thug who uses his money and influences to gain dominance. He was approached by Kanzaki and easily took care of him, and afterward, Himekawa went to handle Oga directly. He kidnapped Furuichi and Hilda, who was later revealed to be drugged (both were seen with severe burns). Oga was flooded from head to toe in his room, and was immediately disgruntled. He went to the warehouse where Himekawa held the two kidnapped friends. He blasted through Himekawa's reinforcements and made his way to Himekawa himself. However, Himekawa turned out to be a more competent opponent than Kanzaki. His weapon was a stun rod. With fluid movements, he had Oga on the ropes momentarily. However, Oga simply stated that the shock he received from the rod was nothing compared to Beel's tantrums. With Beel's power, Oga was able to send Himekawa flying. Himekawa was later shown feeling somewhat bitter in the hospital, along with Kanzaki.
After defeating two of the Tōhōshinki, Oga claimed somewhat of a celebrity status among the students. Although he did not seem any more out of the ordinary, he was commented on by many of the juveniles that pollute the school. Oga takes Beel to the park as what he calls his park debut. There, he meets a young girl wearing glasses and pushing a stroller (Aoi Kunieda in disguise). Oga attempts to become friendlier as he does not want to be thought of as cruel or uncaring.
He sits near the girl and strikes up a conversation, the girl was later revealed to be one of the four Touhoushinki: Aoi Kunieda, the leader of the all-female Red Tails gang.
Although she wears a disguise at the park as a means to protect her reputation, Oga is completely oblivious when the two square off. He is unable to identify her, although it appears as though Beel was able to make the distinction less apparent.
Aoi was the one looking for Oga as he was said to be "breaking a difficult and dangerous balance", an allusion to his complete destruction of both Kanzaki and Himekawa. Aoi quickly proves herself to be a competent fighter, with rapid speed and a clear understanding of martial arts. She wields a wooden sword, and although not an actual sword, she yields the same results as though it were metallic, slicing the window barrings and their reinforcements. Many of Aoi's opponents were surprised whenever she fought with a wooden sword and asked if a wooden sword could actually "cut" things.Oga is quick to the challenge and avoids fighting her. Aoi is shocked to see that Oga is carrying a child, and is thrown completely off guard when he asks her to become Beel's mother. The delinquents surrounding them awaiting to watch the two fight were all shocked as well.
Although it was merely his means to ditch the demonic child, Aoi took this as more of an invitation to become his partner, and as such, she became infatuated with him.Oga's troubled road through Ishiyama continued when the final member of the Tohoshinki was revealed. Oga left his house after Beel showed signs of their severed bonds. He was launched out of his window after showing a hurt and emotional Hilda his theory of leaving Beel. Although he was only referring to the electric shocks, Hilda smashed him through the window and ordered him to leave. While walking through the park, Oga was attacked by Tojo's top fighter in an alleyway. Their fight was only a means of testing Oga's power, and as such, the subordinate left without any signs of anger or tiredness, a statistic Oga picked up on well. A confused Oga wondered about the relation the two shared. The subordinate answered calmly and then exited the alleyway, missing his next hit on Oga (which was sure to be a devastating blow). When Oga awoke the next morning, he noticed that Baby Beel and Hilda were missing. Furuichi pondered this and spoke openly on why Oga was taking the situation so lightly. A jubilant Oga was cut short on his celebrations, and was forced to go search for the two by his estranged sister. Oga went to look by the river-bed as that was where he first found Beel. Tojo and his subordinate were there, and Beel was also present, this time riding on the back of Tojo. A fight ensued, and with that Oga began to notice issues with Beel. His glazed eyes were unfocused and the attachment to Tojo was almost abnormal. Oga concluded that the power he had was enough to draw Beel towards him. Oga demanded to know how he found Be'el in the first place. Tojo answered honestly that he found Beel roaming the streets. He then took a few jabs at Oga's terrible parenting skills. Beel was set to be the prize of the fight, and Oga was quickly beat to the point where he succumbed to serious injuries. Oga took the upper hand, catching him of guard until he noticed the Zebul Spell contract on Tojo's upper arm. Tojo sent Oga flying, then took Beel and left the scene. Oga returned home, bitter and angry, to find Hilda and a ghost-like creature in his stairway.
The ghost-like creature turned out to be the demon doctor, a physician that is in Muumuu form, whom Hilda called to assist with the examination of Oga and Beel. Oga immediately struck a nerve with the two commenting on both their looks assuming they were low-class demons. He wondered why the demon doctor was so animated. The doctor continued his examination of Oga (with a few minor interruption in the form of Lamia his assistant). The doctor determined that the severing of the bond was because Oga was not powerful enough to keep up with Beel. A bruised Oga relinquished his role as surrogate father momentarily, in an attempt to regain his strength. Oga wondered aloud whether Beel was better off with Tojo. He was snapped back into reality by Hilda and his fighting spirit eventually returned.
While taking a shower, he was interrupted by Kanzaki's subordinate. He is told to follow him to the scene of a brutal battle between Kanzaki, Hajime, and Tōjō. Tōjō utterly defeated Kanzaki and Hajime with help from his own subordinate, a bespectacled man with apparent power. Kanzaki and Hajime are forced to work with Oga in an attempt to defeat the mighty Tōjō. Oga does not take to this smoothly however, and with blatant disregard, he tries to turn down the offer. However, he sees reason and the three make their way to the school.
Unfortunately the trio is ambushed by local gangs, a tactic used cleverly by Tojo. Kanzaki and Hajime fend off two opponents each and were dumbfounded to notice Oga handling the rest on his own. Unfortunately, the thugs continue to emerge, and the trio find themselves growing tired. Aoi jumps in and fends them off one by one protecting the three from further harm. Her group, the Red Tails, is also present and Aoi tells Oga to continue on ahead and find Tōjō.
Oga runs into the school looking for Tōjō. On his way, he notices fireworks being set off, and he continues on his way towards the location of the fireworks. When the two meet, Tōjō reveals that he figured out that Oga's the father of Beel. He inquires to return it, stating that perhaps a fight over him would be more suitable. Oga states his relation to Beel being more caring and out of friendship, then going to say that it is up to Beel to decide. The once warped Beel regains his composure and glazed look, and he creates a demon circle with strange markings. A forcefield is created and the electricity it generates prevents anyone from entering. Oga penetrates the shield, doing more damage to himself. He gives Beel the same cocky smile he gave him during their training sessions. The two bonded once more and a "revival" of their core was created.
Oga now deals with Tōjō. The fight between the two was full of complacent blows and rigorous hits. Oga had Tōjō on the ropes momentarily and intended to land a strong hit to his midsection. However, Tojo repelled the attack and made a blitz behind Oga with a killing blow in mind. Oga dodges and sidesteps him and returns to Beel and Furuichi's location (Furuichi being there on his own accord). Beel feeds Oga some power, and the contracting Zebul Spell is generated. Oga tells Beel to stay away from the fight, including his help with any Zebul Spell or magic of any kind. Beel realizes this, and he sinks his power back to himself. Oga continues his fight and takes a blow from Tōjō on purpose, as a means to get behind him and engage a suplex-type move, crushing Tōjō.
An exhausted Oga limbers back to Beel stating his win, and the two lock eyes. Oga then notices that his arm deformed during the fight. The magic built up and released straight through his arm. The blast destroyed the school and the trials at Ishiyama High concluded with Oga reigning victory over the Tōhōshinki.
Saint Ishiyama High Arc
Because Oga destroyed Ishiyama High, the delinquents from Ishiyama relocated to different schools, several of whom were relocated to Ishiyama's sister school, St. Ishiyama High. The people relocated included Oga, Furuichi, the Touhoushinki, their subordinates, some members of the Red Tail and the notorious MK5. The group was relocated for the time being while the school was reconstructed, as there were no other alternatives. The students of Saint Ishiyama were displeased by the presence of the delinquents. Oga and the others were immediately targeted and subsequently harassed for the most of their time at Saint Ishiyama.
Their presence was monitored through rotations, and the other students avoided the Ishiyama High refugees. However, there was one St. Ishiyama student, Kazuya Yamamura, who admired the delinquents, especially Oga and Furuichi, as he thought that they both defeated the Tohoshinki, when in fact it was only Oga. Kazuya even went so far as to meet Oga early in the morning at his house, much to Oga’s dismay. Hilda was impressed to see Oga's "underling", telling him that he was "moving up in the world". Later after a fight with a rival school, Oga and Aoi, who was involved in the fight, were called to the principal's office. To keep up appearances, the two weren't expelled but instead chosen to keep the other Ishiyama students in line.
Despite being told not to go near the St. Ishiyama students, they went to visit Kazuya and were surrounded by two of the Rokkisei, Ichiro Shinjou, and Mitsuteru Sakaki. Knowing they would get expelled for fighting, Aoi and Oga both outclassed them without resorting to violence. Aoi sliced off the end of Sakaki's bokuto with a ruler. Oga dodged all of Ichiro's punches while asking him questions. After realizing their defeat, Shinjou and Sakaki decided to leave. Heading back to their classroom, they then heard that Hajime had gone to avenge Shiroyama for getting unfairly beat up by some Saint Ishiyama students. Aoi and Oga arrived just in time to see Hajime badly beaten by Hisaya Miki.
When Nene tried to pick up Hajime, she was taunted by Miki and was held back by Oga when she tried to attack him. Before the group left, Miki asked Oga and his friends to come to the school rooftop to fight. After showing up, the Ishiyama delinquents found four of the Six Holy Knights: Miki, Sakaki, Ichiro, and Hiromichi. At first, Oga stated that he would fight all of them. He was joined by Tatsuya, Aoi, and Shintaro. Each began their own fight while Oga defeated Ichiro with one punch. Afterward, he began to fight Miki, but he was seemingly immobilized after being hit with Miki’s special move. Hajime jumped in to fight Miki and was sent flying by Oga. (Miki said that if Kanzaki had continued to fight, he would have been severely hurt due to his old wounds. Oga claimed that he did not know anything about this. His only reason for knocking him out was apparently to move him out of the way.)
The fight between Oga and Miki resumed. Miki prepared to show Oga his special move but was stopped by Shizuka Nanami and Kaname Izuma. Tōjō arrives to fight and withstands Miki's attack to fight Izuma but is dissuaded when Izuma releases dark energy. The next day, Oga's name along with everyone who was present for the fight are put on the suspension list, except the Rokkisei, but are given a chance if they defeat them at a volleyball game during the festival. After being tricked into playing, initially not caring for Hilda's edited flim, Oga skips a day to fight Miki but is defeated by the Izuma style finisher (the Black Owl Killer), although this attack is strong enough to take down Oga in one hit, it must be stressed that Oga actually intended to take the blow to measure Mikki's strength, and made no effort to dodge it.After his pride is hurt, he spars with Tōjō in order to make a new move. The day of the festival arrives as Oga finishes his new move, and the volleyball match begins. After having a rough time, they use Beel to feint and won the game, but after their victory, the school is attacked by one of Oga's old enemies. Miki moves to fight the opponents and is at first overwhelmed, Oga, realizing that Miki can't take them all on by himself, joins in the fight, The others go after the enemies holding people hostage. Oga almost blew his secret but is covered by Izuma, who knows about demon powers. At the end of the festival, Ishiyama is accepted as part of the school.
Prince En Arc
After the invasion by Kariya is over, Oga is seen talking to Hilda about Izuma knowing about demon energy and the next day heading to school remembering how he never got any info on Izuma while at school he is seen being greeted by St. Ishiyama students, then being asked by Miki to walk home together (but quickly refuses him). He then later goes to the roof to confront Izuma himself while meeting Toujou at the same time, but before they fight all three are attacked by Zenjurō Satome (his new homeroom teacher) and is brought back home. Later as baby Be'el slapped him back to life in class he then goes with Furuichi to get something to drink, feeling Zenjurō's energy as he closes the wormhole Oga made during the festival. Feeling the energy, he travels to the gym as Zenjurō is leaving after restraining Hilda as Zenjurō leaves he tells Oga to come to school tomorrow. He is then confronted by Kuineda about who baby Beel is; as he tries to explain, he hurts baby Beel's feeling because he doesn't remember his full name. Baby Beel runs into a wet nurse who looks like Hilda as she knocks out Furuichi, who was listening in. She tries to kiss Oga, but is blocked by the real Hilda.
As two other wet nurses come in, a boy named En appears, claiming himself to be Baby Beel's brother. Before he can say more, they move to Furuichi's house. After explaining his purpose to destroy the world with Beel, En and his wet nurses soon disappear after explaining that some of En's men will come for Oga's life. As Oga, Hilda, and Kuineda head home, a moment of silence came. When Kunieda had to split because her home was the other direction, a demon suddenly appeared and caught her. Oga and Hilda came up with a plan to save Kunieda, with Oga acting as a bait so Hilda could save her. The plan went just as planned, but the demon read their tactics. Hilda got pierced with the demon's spear, right through her stomach. Falling helplessly on the road, baby Beel was about to cry until Oga stopped him, saying that Hilda was still watching over him. Oga comments that even though she has a hole on her stomach, her concern was still Baby Beel. Enraged because of what happened, Oga fought the demon even though there was no use fighting. Zenjuro suddenly appeared and stopped the demon before it was too late for them. Hilda was soon taken care of by Lamia and Dr. Folcus. Later that night, Hilda apologized to Oga saying that what happened earlier was a pathetic story. She was planning to say more, but inadvertently fell asleep. After being defeated easily, Oga takes up Kuineda's grandfather's offer for training. After completing his training, he then started training with Zenjurō, fighting a copy of baby Beel to be able to use his demon powers.Once Oga finished his training he went to where Hilda and the others were to fight the demons, holding Alaindelon like a sword and when the fight begins Oga shows all his power defeating the demon, who had previously defeated him and Hilda, with one shot. He then turns to the two remaining demons and claims to show them a new skill to beat them at the same time. He then takes a long time preparing a milk bottle, bringing its temperature down, and to everyone's surprise, drinks it himself. He calls the skill "Super Milk Time", which he accidentally invented during his training with Saotome. Hilda realizes that he had "forced a synchro", or synchronized himself with Baby Beel.
After a while, he drinks a bit more milk, causing a complete synchronization, uniting himself and Baby Beel into one body. However, with Beel, not Oga in control, the demons are defeated, but Himekawa's apartment building is completely destroyed. Prince En leaves with his nurses and Behemoth's demons after making a fit over his interrupted game. Furuichi's act of guarding Lamia from the falling ceiling, declaring that he would be back one day with a whole army to crush them, is misunderstood.
Akumano Academy ArcThe day after the fight, Oga is seen unconscious with Beel at his side. After the fight with Behemoth's fellow, Oga and Beel faint. When they woke up they exchange their bodies, so Oga is stuck in Beel's body and Beel is stuck in Oga's. Together with Hilda, Oga goes to Saotome's place so that he can help him and Beel returning to their respective bodies. Anyway, Beel in Oga's body flees and meets Aoi. He hugs and stays close to her, and because of this, Hilda gets jealous. The two women fight on the roof, but this time, Aoi is stronger after her training, and beating her is not a simple task for Hilda. Suddenly, Oga ("Beel") hugs Aoi and she blushes; Hilda gets even more pissed, and Beel("Oga") also wants to stop Beel-Oga. The 3 attack Beel-Oga at the same time, but in that instant, Oga returns to his own body, resulting in him being hit. Later Oga meets an old man who was searching for him until that moment. Oga doesn't mind the old one and says he's not Oga at all. The old man then is revealed to be Behemoth, and after fighting with Saotome, the school principal Genma Isurugi, and Aoi's grandfather Ittousai Kunieda, he reveals to have rebuilt Ishiyama High and renames it as Akumano Academy, a school of demons. After that, Behemoth claims to not be the Army Leader because of his advanced age. The actual leader is likely the son of Behemoth (he calls him "Pops"), Jabberwock. He kidnaps Hilda with his dragon Sodom, and flies away with his father on the "pet's" back, while Oga is unable to follow him because of Ittousai blocking him on Saotome's order. But Oga manages to free himself and goes after Jabberwock and Behemoth on the dragon's back. He goes in Super Milk Time again, first drinking 30cc and attacking Jabberwock. Anyway the army general is too strong and easily takes on a triple 3-Hit Zebul Emblem Combo from 30cc Oga and even drinking 50cc of the milk, Oga can't keep up with him. So He decides to hit the dragon and free Hilda; The wet nurse orders the BoB Brawler to go away by himself but Oga's resolute, and hits Sodom with a 6-Hit Zebul Emblem Combo. The dragon actually releases Hilda from his mouth, and she uses her demon aura to catch Oga. After she tells him he's a damn fool, she says that he must take care of Baby Be'el, being the only parent he has in this world. Then she gets swallowed by Sodom, letting Oga fall down.
After that, Baby Beel found a bunch of croquettes. He and Oga then used "Super Croquette Time". They then flew into Sodom's mouth and saved Hilda. Later on, Oga brought down Sodom and used an enormous Zebul Emblem, finishing him. This made them disappear and destroy the newly-built school.
When Oga and Baby Beel woke up, they found themselves in the Demon World. After that, Alaindelon transferred them back to the Human World. Just then, Hilda announced that the Great Demon Lord called off the destruction of humanity. They were then dissmised, returning to the Demon Lord, but Baby Beel refuses to return. Hilda tried to console him, saying they can take all the things Beel likes with them After that, Baby Beel and Oga had to say good-bye. While they did, Oga said, "If you want to come back, then punch the lights out of that Demon Lord and come back on your own." Yolda appeared, ready to take them back. Oga rubbed Baby Beel's forehead as the two said good-bye. Later on, while Oga and the other Tōhōshinki are fighting deliquents by the riverside, Alaindelon appears. Baby Beel emerged from inside of him, with Hilda in tow. They announced that the Great Demon Lord couldn't make up his mind again, allowing Baby Beel and the others to stay.
Oga and Tōjō finally confront the army's leader. As the fight starts, Oga and Tōjō cooperate to defeat the powerful enemy, dealing powerful blows such as a full power Zebul Blast and a German Suplex, to which Jabberwock easily resists. After having knocked out Tōjō, the fight becomes a one-on-one between the Demon Lord's father and the Army's general. Oga unleashes Beel's Demon Power, drinking all of his milk, but Jabberwock is still stronger than the BoB Brawler, and apparently defeats him. Just before fainting, Oga stands up, and says he's not done yet, and deals a powerful kick enough to make his foe fly for a good 33 feet. Jabberwock claims that Oga's power has finally been "awakened", but Oga denies this, saying that his newly found strength is not due to such an easy power-up, just him trying harder to protect Beel. Lamia says that Oga's strength is due to the him becoming stronger together with Beel, since Black Techs accelerated Beel's maturation process.
Memory Loss Arc
On the morning after the fight with Jabberwock, Hilda wakes up, having lost her memory Oga and the rest of the family have to explain to her who she is, by their point of view, making Hilda believe that she is Tatsumi's wife and Baby Beel's biological mother. Hilda even makes Oga a bento when they go to school and forces Beel into clothes.
As they try to regain Hilda's memory, one of the pillar squad communicates with them (Oga, Furuichi and Yolda) by using a computer. He said that the only way to recover her was to kiss her. At first, they thought it was a lie. But then, he said that every woman needs a kiss from her Prince Charming. With an answer like that, Oga thought that it was him to be kissing her. He then proceeds to smash the computer with the keyboard. Oga asks Furuichi and Yolda whether they heard or saw anything from that event, because he can't accept the truth if he was the one to be kissing her. Then, Yolda tells Kunieda, the rest of the Red Tails, Himekawa, Kanzaki, Natsume, and Good Night about the kiss. They chase Oga and tell him to kiss Hilda.
While he was hiding behind the bushes, he met Lamia who brought the antidote for Hilda, who was missing. Oga used Baby Beel to locate her and found her by the river. Then, a few pillars who were fishing crayfish met Hilda and wanted to exact revenge after all she had done to them. She didn't understand anything at all, being a wet nurse and serving a son to a Demon Lord. Furuichi and Yolda were shocked. Oga stopped them when they tried to go to Hilda. He went to her by himself and kicked the pillars into the river. He talked to Hilda about the antidote and she said that she will take it. But then, Baby Beel threw the antidote into the river because he didn't want Hilda to turn back to normal. Oga didn't mind at all. He said that it's okay if she stays like that forever because the good thing now is that her cooking is better than before.
He gave Baby Beel to her and said that she was his mother after all. Baby Beel kissed her. Then, she asked Oga whether her cooking was really that bad. He replied by saying that it was almost attempted murder; like a chemical weapon. Suddenly, Hilda remarks, "Do you think you've actually grown a pair, bitch? Fine. Next time, it won't be attempted murder!". Oga freezes when he finds out that the 'Prince Charming' was actually Baby Beel, and that she had turned normal as he insulted her cooking. Hilda then attacks him.
Field Trip Arc
Hero Show Arc
Oga and Baby Beel notice Furuichi in the hallways at Saint Ishiyama Academy. Knowing that he will be going to the infirmary, Oga runs over to him and asks that he buy bread along the way. He ignores Furuichi's remarks and asks that he specifically buy melon bread, only to be told that Furuichi won't buy him any.
The two end up going to the infirmary together; while on the way, Oga comments that the new tissues stuffed in Furuichi's nostrils suit him. Suddenly, Furuichi begins rambling about a flower-like scent and about a bug that just landed on Oga; Oga, who does not smell or see anything particular, thinks that Furuichi has developed a serious disease. He is then unexpectedly punched in the face. Irritated, Oga tells Furuichi that he needs to face the consequences and kicks him as he runs away. However, Furuichi then turns back to Oga who then starts punching him. Oga is caught by surprise with Furuichi's apparent skill in evasion and is subsequently buried down into the floor. An infuriated Oga rises back up from the floor and, upon realizing that Furuichi is gone, asks Baby Beel about where he went off to.
Oga heads back to his homeroom and asks his classmates about whether Furuichi is there; unfortunately, he is not there, irritating him.
Suddenly, Hilda and Lamia appear behind Oga, prompting him to ask about why there are present; because of a minor inconvenience from the Red Tail, they change their location to the rooftop of a nearby building. There, Oga is told about the tissues that they previously received from the Great Demon Lord and how they summon a Demon from Behemoth's 34 Pillar Division. Oga inquires more but is told to watch Furuichi instead as he returns to his homeroom. He ends up observing the situation from afar, watching as Furuichi gets into a fight with Kanzaki and Himekawa; he also notices the Demon Hecadoth present beside him. While watching the fight, specifically after the Demon Agiel is summoned, Oga begins to find the situation comical and eventually bursts into uncontrollable laughter. He is reprimanded for his behavior by Lamia though he then tells her that he will defeat Furuichi when the time comes. With that said, he sees Tōjō appear with the intention to fight Furuichi, prompting the latter to summon Jabberwock, much to Oga's surprise. This subsequent fight destroys Oga's initial light-hearted attitude and makes him review the situation more seriously, especially after Furuichi ends up victorious. Later, after learning about the toxins in the tissues, he tells Hilda and Lamia repeatedly that he's going to use the bathroom.
Instead, Oga meets with Furuichi at the river nearby. He asks that Furuichi hand him back the tissues and threatens to beat him for it if he has to; upon hearing his response, Oga remarks that he is an idiot. He then tells Furuichi that he will lose even with his Demonic tissues. Afterwards, the two initiate a battle stance, causing them to reflect on when they first fought seriously. The two end up being distracted by which childhood incident was the first time where they fought against each other until both decide to simply start their fight.
Furuichi fights after summoning both Xoblah and Vabam; however, Oga ends up beating Furuichi after both summons which subsequently results in the Demons disappearing. After the second time, Oga finally explains that Furuichi will die if he continues to use the Demonic tissues. To his surprise, he learns that Furuichi already knows and that death is no different than being mocked by their peers every day. After his speech, Furuichi summons Behemoth to the fight. Oga is shocked to see the Demon and, upon realizing how Behemoth's powers are physically affecting Furuichi, yells at his friend to stop. However, they are then engaged in a more evened one-on-one fight that eventually finds its way to the river waters; there, Oga uses Super Milk Time. He and Furuichi clash furiously in the river until both stop and the waters engulf them both. Afterwards, Oga swims ashore with a now unconscious Furuichi on his back. Once he sets him down, Oga states that he remembers the first time they fought against one another before ultimately collapsing.
Unconscious, Oga's body is treated by one of Lamia's Muumuus. He eventually wakes up and starts walking towards Furuichi, ignoring Hilda. He asks for the tissues again before telling Furuichi that he is strong enough without the tissues.
Suddenly, they are approached by the members of the Shadow Force who appear ready to get their revenge on Oga. Despite his injuries, Oga faces them. However, he is then surrounded by several of his peers from Ishiyama and even Miki; together, they all gang up on the Shadow Force and eventually take them down.
Once the fight is over, Oga offers to help Furuichi "apologize" to Kanzaki and Himekawa but he ends up having a sore body afterwards. Later, the girls of the Red Tail start making fun of Furuichi again for being a supposed lolicon; remembering Furuichi's speech from earlier, Oga tells them that they should stop teasing him as he does not appreciate it. Nene assures him that they know and later mentions that she is jealous of the friendship that he has with Furuichi, surprising him.
On the way home, Furuichi returns his tissues to Oga who refuses to take them back because they are wet from the river waters. Hilda takes them instead and Oga kicks Furuichi's side for making him worry earlier.
Saint Saint X'mas Arc
Flashbacking about Oga's ruined childhood about Santa Claus, Hilda, who is told by Misaki that she and Oga to be Beel's Santa and should pick a cute present for him, suddenly gets excited about it and even made a list ---- he's soul, 15 loyal servants and a 180m tall Demon World Monster Gorgonzola. Hilda then concludes that the Gorgonzola should be a definite winner, so he should go to the Demon World and capture it with Beel. Oga, who don't want to go to the Demon World and do such pain, insists that a mechanical pencil would do. Thus they started to argue, and ended up with Hilda accidentally kiss Beel and Hilda's 'amnesia' personality returns. Shocked, Oga tries to get Beel to kiss Hilda again, but after thinking about the current situation, concluded that this would be better so he wouldn't have to get Beel anything demon related.
Then they later on saw an event notice in St. Ishiyama --- "Couple Limited: Saint-Sent Christmas" also known as "Best Couple Grand Prix". The two enter together for Beel's sake(and of course because its free), much to Aoi's dismay as she was planning to invite Oga to enter with her.
The first event which was the "Three-legged-death-match", resulting Oga using Beel's power in order to get to the second round along with their friends. The next round was organized in tournament format. Oga and Hilda's next challenge was to fight against Oga's teachers, Zenjurou Saotome and Suiten Ikaruga. Ikaruga introduces herself as Saotome's wife -- thus the announcer concluded this was indeed the fight between Ishiyama's Strongest Married Couples (as they thought). The two babies -- baby Beel and black Beel start fighting. Ending up baby Beel and Hilda accidentally kiss again. While on the other hand, Oga and Saotome is talking about how it is better that she has amnesia as Saotome knows Hilda hates him much that she would barely destroy the gymnasium and kill him. Hilda intervenes their conversation, asking them if she should destroy the gymnasium -- however both of them would get caught in it as well. Both of them are shocked as Hilda returned back to normal.
However, the announcer reveals what kind of challenge they would be taking, "Heart-Pounding Glued-Together Balloon Breaking Game". Partners should put the balloon between them so it will not fall, they have to wear sandpaper gloves meaning if they touch the balloon it will pop. The pair that pops the other pair's balloon will win. Hilda, who doesn't know and care much, said that shouldn't dawdle. So Oga explained, and then Hilda agrees to take the challenge and said they should win whatever it takes.
The fight starts with the two pairs jumping high above, the two men start fighting the same way the two infants did, while the two women start a verbal war. Saotome laughs, asking if Oga has trained enough, he then punches Oga resulting the Oga-Hilda pair to fall down. However, Hilda uses her demon powers to break the fall. Ikaruga uses 'fox fire', which Hilda blocks and both of them manages to dodge the explosions. In the end, the Oga-Hilda pair managed to win by using teamwork ----- but mainly Baby Beel as bait.
Oga and Hilda manage to get to the semi-finals, along side with the other Ishiyama students. In which they are to challenge the Toujou-Nanami pair in a game of "Twister Karuta". For this challenge, the women face off -- trying to get the card that the speaker says before the other person. Written on the card is an attack, where the men would use to get the other off the mat. Hilda, not knowing how to play, gets the wrong cards - allowing Shizuka to easily win for Toujou to attack Oga. Hilda does manage to get a card, but the card had a useless move.
Shizuka then grabs the right card with the attack 'chop' written. Tojo smirks and proceeds to chop Oga, however to their surprise, Oga had ripped the map. He didn't move at all but because of the force Toujou had did the map was ripped. That challenge resulted in Toujou and Shizuka's loss, as Toujou's feet has stepped out of the map.
Their final challenge, is the 'Head on Battle', which the aim of the challenge is to steal the other pair's star. Since Izuma lost the motization to continue (because Shizuka lost), Aoi resulted to be partnered with Aiba. The battle starts, however Hilda gets distracted by the sense of Demonic power from Aiba and warns Oga. Resulting Hilda to lose. However, Oga gets distracted too because Hilda's unexpected lost, and Aiba gets their star, saying he lost because he was underestimated by Oga. But baby Beel already had taken Aoi-Aiba's star. Thus, it is a draw. The fight continues again. Both pairs start to move at the same time, Aoi gets pushed back by Hilda using her left eye since she sees too well with it (Aoi tought it is a blind spot). Surprised Oga and Aiba, Oga gets serious then, stating the one who was underestimating someone was Aiba himself. Oga proceeds to attack, finishing Aiba with a 'Merry Crunchmas'. Oga and Hilda collects the stars, and are announced the charmless best couple.
Returning home, the family wait in front of the christmas tree for Santa. Hilda asks what Beel would like for Christmas - which she claims is the Gorgonzola. Oga retorts, saying Santa would never as big as that and that the only thing Santa would have are mechanical pencils - since he had that until sixth grade. The two break off in yet another argument, however Beel calms down, explaining (somehow) that the star Oga and Hilda had worked together to get was the best Christmas present ever.
Return to Ishiyama High School Arc
While Oga has breakfast with his family, he hears from his mother about a "trial" nursery school that has recently opened up nearby, which she suggests would be a good place to take Baby Beel. Oga is interested in the idea and takes a look at an application form for the place.
He is eventually inquired about Baby Beel's age which, as Oga suddenly realizes, he does not know himself. Oga later goes to Hilda and asks about the infant's age. There is a slight misinterpretation regarding Oga's words which causes him to wonder whether Demons actually count in years; he learns that they do, as well as the fact that Baby Beel is nearing three years old. He furthermore discovers that Hilda is the same age as him, which ends up making him feel slightly uncomfortable.
Sometime later, Oga fills out the application form and shows it to Furuichi while eating a snack, moreover explaining about the "trial" nursery school. He berates Furuichi when he reminds Oga about the fifteen meter limit between him and Baby Beel; as proven before, this limit has since been loosened.
Oga and Baby Beel head outside to prove this point to Furuichi. After demonstrating that they can be apart for at least eighteen meters, he reminds Furuichi about the toy car incident from before, then adds how he might actually be rid of Baby Beel if the infant can embrace the idea of a "trial" nursery school. An argument situates between the two teenagers when Oga's previous words about accepting his fate as a Demon Lord's parent is brought into subject. After Oga states his reasons, which was that most parents do not even spend time with their children at all times, he eventually gives in and begins assaulting Furuichi; during so, he casually admits that he knows about Furuichi revealing Misaki's past.
Oga and Furuichi eventually take Baby Beel to the "trial" nursery school.
Oga is soon approached by a delinquent who deliberately attempts to start a fight with him; though ready to respond with violence, thinking that it can all be settled with a single punch, he is forced to stand aside by Furuichi. He eventually brushes off the issue and sets down Baby Beel, telling him to make new friends with the other children. However, as the children are all playing, he notices the previous delinquent making a hostile move towards Furuichi. Oga shoots him an intimidating glare and continues to keep a watch over him. Shortly after, he notices that Baby Beel is being bullied by one of the children, causing Oga to turn his attention to them and observe the subsequent events. Oga praises the Demon Lord for his patience though he then becomes surprised by how level-headed Baby Beel can actually be. Oga then overhears the same delinquent from before laughing at him and Baby Beel; however, he says nothing.
Sometime in the afternoon, Oga and Baby Beel head home together. Along the way, they are approached by the delinquent from the "trial" nursery school and his little brother, who happens to be the one that bullied Baby Beel. Oga is indifferent to the former's words and condescending actions even after he realizes who Oga really is. This remains true even after being told that, with the newcomers flocking to Ishiyama, he will lose his title as the strongest. The delinquent then lunges at Oga. The child-rearing gang leader subsequently tells Baby Beel that he will demonstrate how to make friends, before Oga then punches the attacking delinquent, easily sending the latter flying several meters away. As Oga looks on, he proclaims that even with the "revival" of his original high school, all of the newcomers can simply come at him.
Later, while Oga is asleep on the first day of the new year, he has a dream involving three objects supposed to indicate good luck: a hawk with an eggplant head that has "Fuji" written upon it. Oga becomes excited though he is berated for such a visionary by an imaginative Furuichi. The unusual hawk suddenly snatches Baby Beel from Oga and begins flying away from the teenager; surprised, Oga begins calling out for the Demon Lord. As that happens, his real body falls off from his bed, abruptly awakening him. He then groggily wonders what it behind the abnormal dream.
Oga and Furuichi eventually head over to the Kunieda residence for a small festival. They, along with Baby Beel, briefly pray to the Gods, albeit in a very informal manner, before helping themselves to the food. Aoi soon accompanies them. Oga feeds Baby Beel and elaborates to the other teenagers about the dream that he experienced earlier. Still confused about its meaning, he has Baby Beel draw a fortune cookie, per Aoi's suggestion, though his message reads "radish". Oga becomes comically outraged at the apparent scam and demands a refund. However, his temper subsides after Aoi brings up the new semester back at Ishiyama.
Sometime after, Oga and Furuichi walk to Ishiyama High School together, with Baby Beel clinging onto the former's back. Oga openly states his annoyance at having to return to a high school filled with overbearing delinquents; as he says that, both of the teenagers arrive at the school entrance, where the see the entire MK5 buried into the concrete wall. Oga is initially annoyed at the sight, though he then begins to feel impressed, noting on the clean "burial" that was given to the five delinquents. The matter is quickly brushed aside and the two teenagers enter the school courtyards together.
They enter one of the school buildings where they meet with Kanzaki, Natsume, and Shiroyama. Oga and Furuichi are informed that several students have been rising in both power and status at their previous high schools; moreover, now that everyone is back, they're after strong delinquents, particularly Oga. Natsume warns Oga to be careful about that. However, after Oga swiftly buries a delinquent ready to attack them from behind, he assures them that he will be fine, then walks away with Furuichi chasing after him.
Oga and Furuichi soon encounter Himekawa who provides them with similar warnings. However, he tells Oga that there are three first-years with a reputation comparable to him, and he states their names: Fuji, Takamiya, and Nasu. Afterwards, Oga notices that someone has drawn over his Zebul Spell tattoo. Himekawa elaborates further on the three first-years and adds that Oga might not even care about what he is saying; after that, he leaves. Furuichi responds with a similar statement about Oga's strength. Oga responds by kicking Furuichi in the shin and warning him that he is also a targeted individual. He also adds that since arriving, Baby Beel has become very agitated, which he moreover claims is the "face of a true man". Oga then looks back at his defamed Zebul Spell tattoo and remarks on how things will be getting rough.
He and Baby Beel return to the previous hallways where they encounter a tall teenager amongst Kanzaki's gang; evidently, he is the same person whom Oga buried before. Oga raises his right fist and asks whether he is responsible for drawing over it. The tall teenager responds by introducing himself as Yōhei Nasu and complaining that Oga's punch was "tiring" upon him; therefore, he decided to tag Oga's fist. Oga tells Nasu that he will sing him a "lullabayo" and allows himself to be hit beforehand. Oga is subsequently hit with a powerful uppercut and effectively buried into the ceiling above, where he is left to dangle from.
Despite so, he can hear the conversations being held in the hallways, and eventually he becomes annoyed. Oga states this to the delinquents below and begins pushing himself out from the ceiling. He eventually frees himself and lands on the ground, where he catches a falling Baby Beel with his hand. Oga proceeds to ask Nasu about "how much he knows" though he does not elaborate on what he is referring to.
Before he can say anything else, things take a sudden twist in the situation, leaving Oga seemingly forgotten. Annoyed, he draws everyone's attention back to him, punching and destroying the wall beside him to prove a point. His act is done in vain as Nasu is subsequently forced to leave with the other Poltergeists; therefore, their fight will be held off. Before Nasu leaves, he warns Oga that his gang will take down everyone who came back from Saint Ishiyama Academy, as well as that he will steal Baby Beel from him. As Oga reflects on Nasu's words, suddenly, Baby Beel begins pulling on his hair and effectively tormenting him; this causes Oga to yell at Baby Beel, as well as Furuichi, when the latter casually interprets a reason as to why. Oga then notices a delinquent in the hallways telling him to watch out. He is then told by another delinquent that he is Ebian Ichikawa. This same delinquent gives his own name, Kankurō Akahoshi, before telling Oga that he will someday reign over Ishiyama, even if it means defeating him one-on-one. Oga looks on as both of the delinquents walk away from him.
Oga and Furuichi later visit the Kunieda residence to discuss their next steps regarding the newcomers. While preventing Baby Beel and Kōta from fighting each other, he reveals his presence to Aoi, unintentionally startling her and resulting in a slap to his face.
The three attend a meeting sometime after involving several of their Saint Ishiyama classmates. After a brief distraction, they all begin discussing Nasu and his motives, though Oga remains silent for the most part; despite so, he reflects on Nasu's words earlier about taking Baby Beel. Aoi later comes up with a plan: all of the boys can deal with the Sōrei High School delinquents while the girls handle Majōgari Academy's students. Oga finally speaks up afterwards and tells Aoi that he has been planning to do that all along. Furuichi later elaborates on the plan; they will first gather information on their enemies, namely Nasu and the Poltergeists, before a decisive battle between each party's leader takes place; moreover, Oga is immediately chosen as leader. A dispute follows regarding that scenario involving Kanzaki and Himekawa. However, after a game of rock-paper-scissors, it is decided that Baby Beel will be their alliance's leader. Oga sarcastically congratulates everyone for letting it happen.
The following day, with Baby Beel clinging on to Oga's shoulder, he bursts through a room inside Ishiyama, where he finds Kanzaki and Furuichi with the Sōrei High School delinquents. He notices a bloodied Kanzaki rising from the ground and subsequently tells Nasu not to underestimate his Kamikaze captain.
As he says that, a glowing Zebul Spell appears over Kanzaki's back, with a number 1 imprinted over it; however, Oga subsequently reveals to Kanzaki that he doesn't know how it came to place. The two are then fortunately explained about it from Hilda, who somehow sneaked inside the classroom with Alaindelon. As it turns out, rather than a Zebul Spell, on Kanzaki's back is truly the King's Crest, which signifies that a lifelong alliance has been made between the two teenagers; upon hearing this, Oga becomes surprisingly excited and starts to gloat over this apparent achievement.
Oga's light-hearted attitude quickly disappears after Kanzaki leaves to challenge the Poltergeists; before he does, he tells Oga that he is no one's vassal, and that Oga can deal with Nasu alone. Oga eventually confronts Nasu on another side of the classroom where he asks the latter numerous questions. Unfortunately, he does not receive an answer for any of his questions, though he ends up discovering that Nasu is actually a Spell Master, surprising Oga.
This confusion temporarily distracts Oga, allowing Nasu to immobilize him using one of his Spells; shortly afterwards, he launches himself towards Oga and begins punching him rapidly. Oga eventually manages to break free and deals a strong punch to Nasu which causes him to crash into a cupboard, destroying it. Oga remarks that he learned too much about the particular Spell from Saotome and threatens to force answers out of Nasu's mouth with brutal force. He then adds that he shouldn't have expected Nasu to remain incapacitated after the punch when the latter rises up.
To Oga's surprise, two identical clones of Nasu then appear, distracting him yet again; this allows Nasu to attack him with physical attacks using a rather unorthodox style. He is then rebuked for his previous arrogance. Nasu then proceeds to explain to him about Spells as he begins to harness his Demon's power. Oga is stunned to see Nasu using such power as a Spell Master. He attempts to save himself from an oncoming Spell using a Zebul Emblem for support though he discovers that Nasu's own Emblems are dispelling its properties; when he realizes this, he is pushed against a wall, where Nasu then proceeds to viciously beat him to a pulp. Afterwards, Oga lies nearly unconscious on the ground being forced to listen to more of Nasu's speeches.
He still eventually rises up and brings himself to use the "Father Switch". Afterwards, he punches Nasu, telling him that his words are incomprehensible. Oga tells a now-bloodied Nasu to stand up and discover that his initial words about dominance are meaningless; however, he is instead called out as a "cheater", then inquired about the supposed "Father Switch". Oga receives another oncoming attack, though he manages to successfully block it, then he attacks Nasu using a series of hand-to-hand combat, all the while explaining to him about what the "Father Switch" really means. He remains standing afterwards and simply looks on at a nearly-defeated Nasu. Suddenly, Nasu's body begins behaving irrationally and uncontrollably, somehow resulting in him creating nearly thirty clones of himself. Oga still retains his patience despite the absurd change of situation and tells Nasu to keep on fighting. He ends up drinking 600cc which causes him to enter a combination of Super Milk Time and the "Father Switch"; using this to his advantage, he rapidly punches Nasu and his clones into the ceiling, effectively burying them all, and leaving Oga as the victorious one.
Oga realizes that he forgot to ask about Nasu's Demon and begins to look for Hilda, only to realize that she has left. Hilda eventually returns and informs everyone that there is a possible mastermind behind everything; moreover, it appears as though the next Spell Master is already after Oga. Even so, Oga remains confident in himself.
He soon realizes that he is still merged with Baby Beel and separates from him. Unfortunately, due to having merged with the Demon infant for an extended amount of time, they have swapped bodies again. This revelation heavily worries Oga especially after Baby Beel unexpectedly runs off with his body. Oga, still inside Baby Beel's body, runs off after himself and forces Furuichi to search with him. They cannot find him despite searching vigorously, causing Oga to enter a state of paranoia, going as far as to attack Furuichi for supposedly being too oblivious of the real dangers of the situation; apparently, Oga's reputation is the most at stake. The two continue searching and they end up meeting Aoi whom Oga explains his situation to.
The conflicts between Aoi and Ringo then occur; while watching the two women clash, he admits that they are rather terrifying. His shock soon directs itself towards his true body when Baby Beel is revealed to be half-naked and restrained; utterly horrified, he repeatedly shouts at Ringo for degrading himself to such a level. His constant outbursts eventually result in him being slapped across the face and thrown on the ground.
Oga then remains on the sidelines as he watches an actual fight ensue between the two women; upon seeing Ringo's strength, he becomes worried for Aoi, then concludes that Ringo truly does have a Demon with her. His suspicions worsen after he hears Ringo talk about giving others power which he assumes is related to the King's Crest. Aoi is then given an ultimatum where she is told to fight either Oga or Nene for the other one's safety; such a demand shakes her up and she finds herself unable to rise. Oga breaks from his watch and rushes in, blocking an oncoming attack from Ringo. He tells Aoi that no one is blaming her and says that she needs to fight. He also adds to Baby Beel that he should man up for the women fighting for him.
Not long after this, Oga watches as a King's Crest bestows itself upon Aoi's chest, alarming him. He does not verbally comment on the matter and instead resumes watching Aoi continue her fight against Ringo; during this period of time, he realizes moments after Ringo was threatening his physical self that she was intending to harm his body, albeit as a late reaction.
Moments before she does this a second time, both Oga and Baby Beel switch back into their true bodies again, just for Oga to then sneeze and blow away part of the duct tape on his mouth. When Ringo speaks to him, he tells her to stop. Oga rises from the ground, easily breaking free from the restraints around his arms and ankles, then he pulls out the small rope attached to the collar around his neck. He tells Ringo that he is no longer playing as her hostage and that he is now an observer in her match.
Ringo becomes enraged at his words and angrily reminds him that he is her hostage. In response, Oga tells her that what her plans are only cheapening the fight and that she does not need to resort to such tactics anyhow; this infuriates Ringo further and she nearly decapitates Oga with a powerful swing from her wooden sword. Oga concludes from the attack that she is a Spell Master and contemplates on what to do. Thankfully, Aoi steps up to continue fighting Ringo and he allows her to do so. As he walks away, he sees that Ringo has brought her entire gang to fight against Aoi and becomes astonished at the fact, noting that they all also have Demonic power with them. Oga then goes to pick up Baby Beel. Following Aoi's victory, she tells the members of the "Reborn Red Tail" that they can rejoin the original gang, which Oga smiles upon.
One night, Oga begins working intently on a sort of project for himself.
It is revealed on the following morning that it was a card game that he has since been playing with Baby Beel. When Misaki tries telling him that his classmates are present, Oga tells her to be quiet as he continues playing the game, where he apparently then gains a major advantage over Baby Beel after bringing out a spell card based upon Himekawa's glasses. He then notices his classmates and invites them to play though they refuse. Oga and Baby Beel continue playing the game for a brief time until their antics lead to them being almost completely ignored by Oga's peers; after this, they sit down to listen to a video call meeting held by Hilda. Oga puts on a serious front when Hilda brings up Himekawa in the explanation; however, he then returns to playing his card game with Baby Beel not long after.
Sometime later, Oga and Baby Beel play a tennis match against Tōjō amongst their fellow delinquents; their match leaves them both exhausted and the others surprised that it was taken so seriously. Oga and Baby Beel leave the tennis courts shortly after without anyone noticing them.
The two head back to Ishiyama High School where they enter the territory of the Fallen Angels. Oga swiftly knocks down the guard standing near the entrance and destroys the wall connecting to the inside of the room, casually letting himself in afterwards. He tells the head, Shinobu Takamiya, that he plans to take back his "glasses", referring to Himekawa. However, Himekawa tells Oga that he never betrayed him and that he is only working with Takamiya so that he can gain information for him. Oga immediately believes him and apologizes for causing such a disturbance for him. He then awkwardly walks out of the room with Baby Beel.
Later during the night, Oga reads manga on the couch with Baby Beel beside him. He eventually gets a phone call from Honoka Furuichi who tells him that her older brother has not returned home since leaving to buy pudding; moreover, he did not bring his cell phone so Honoka cannot call him back. Oga informs the young girl that Furuichi is currently not with him. Oga then learns that Furuichi was supposed to be back quickly after his departure, which begins to concern him.
He decides to go to the Ishiyama campus and look for Furuichi there. He is approached by members of the "Hime Boys" though Oga swiftly defeats all of them immediately. After knocking them all out, he realizes that he forgot to ask about Furuichi and then hurries along the school's courtyards.
He stops after realizing that Saotome is present nearby. Oga is surprised to see his former mentor and yells out asking where he has been lately; his loudness forces Saotome to cover his mouth shut and to tell him to be quiet, otherwise he would be caught. Saotome proceeds to tell him that he should not fight either Takamiya or Fuji because he has trained both in the past; therefore, they are supposed to be much better than him. Though initially confused, he is then told more about Takamiya's past, which includes the name of his Demon, Lucifer. Oga then learns that fighting Takamiya and Lucifer using Baby Beel's power can spark a war in the Demon World. Instead of feeling intimidated or surprised, Oga simply states that he is only going to be in a fight, rather than a war, and tells Saotome to stay out of their business.
Oga then heads inside the school buildings where he finds Takamiya standing over a bloodied Furuichi and several other Pillar Generals. Takamiya greets him but remarks that he has arrived late, stepping on the head of Furuichi as an insult to his loss.
Upon seeing the act, Oga jumps upon Takamiya and kicks him directly in the face; his actions effectively commence their fight. Oga immediately springs in for a punch but ends up headbutting Takamiya's knuckles when he performs an actual punch; shortly after, he uses a Zebul Emblem while also dealing an uppercut to Takamiya's chin. He then discards his jacket as he walks up to an injured Takamiya; upon seeing his wounds, Oga becomes surprised that the Zebul Emblem failed to explode earlier. As he looks down at his opponent, Oga sees the Demon Lucifer appear on Takamiya's shoulder and watches her extend his hand out to him. He is then abruptly struck with an uppercut that sends him bouncing around the hallways until he smashes to the ground, momentarily paralyzed and confused from the attack.
Oga's strength quickly returns to him and he conjures several Zebul Emblems in a direct formation towards Takamiya, telling him that he will die. He then causes the Zebul Emblems to begin exploding while he sprints towards Takamyia, hitting him with a powerful punch to the side of the face. Though effective, it leaves Oga exhausted and Takamiya with only moderate injuries.
Suddenly, Oga witnesses Furuichi be pierced through the chest by Lucifer's hand. He then looks on, speechless, as Furuichi's heart is then pulled out from his body, which causes the teenager to subsequently collapse. Horrified, Oga screams out Furuichi's name. However, he sees Lucifer return next to Takamiya while still holding Furuichi's heart. Oga is then told by Takamiya that he can still save Furuichi if he can retrieve his heart before sunrise; just as he says that, Furuichi's heart is sliced apart into six pieces. Oga runs toward him in anger but is forced to stop after the pieces are sent across the school with a blinding flash. Takamiya tells him that he will need to retreive them all from the his subordinates in order to get the final piece from him. However, Oga catches a piece of Furuichi's heart as he goes to pick up Baby Beel. He then looks on at Takamiya with a furious glare.
Oga resumes his fight with Takamiya for the piece of Furuichi's "soul" that he has with him. They engage in a furious and destructive fight, but Oga is left visibly exhausted towards the end.
Fortunately, he sees that Tōjō has arrived but jokes that no one asked him to show up. Moments later, Tōjō punches Takamiya into a classroom; Oga is left speechless and genuinely surprised at what has happened.
Oga is then inquired as to who destroyed the school buildings; hesitant, he eventually states that Takamiya is fully responsible. He then sits back as Tōjō and Takamiya converse, speaking up only when Tōjō incorrectly pronounces the names of certain groups, such as the Fallen Angels or Akumano Academy. Oga also tries to explain about what happened to Furuichi after Tōjō notices him seemingly dead on the ground. However, after believing that Takamiya "killed" Furuichi, Tōjō becomes enraged and begins to fight seriously. Oga manages to convince him from stopping after he tells him that Furuichi can still be saved.
He then explains the situation to Tōjō who ultimately decides to track down the other pieces of Furuichi's "soul" for Oga. In the meanwhile, he asks that Oga send Takamiya flying seven circuits for him. Oga smiles at the deal and watches as the third-year head off to complete his goal. However, Lamia and Alaindelon then arrive to assist Oga but they end up crying after they see Furuichi; annoyed, Oga tells them to stop and begrudgingly explains about the situation again to them. Once he finishes explaining, he tells Lamia that he believes that she can treat Furuichi's wounds. She eventually agrees to help him and prepares to leave; before the two Demons head off with Furuichi, Lamia tells Oga that there are helpers on the way.
As Oga wonders who the helpers could be, Takamiya speaks up and states that it will be interesting to see both of their underlings fight against each other.
The two first-years then resume their fight with one another. Oga charges at Takamiya and evades a kick from him, only to then grab his shoulders from behind, then throw him against a wall; afterwards, Takamiya speculates what Oga is currently feeling about his whole situation. Suddenly, with Lucifer back in the fight, Oga is forcefully suspended towards Takamiya but he manages to block an incoming punch. Holding Takamiya's first in his hand, he states that he is not scared at all, and that he can now concentrate on Takamiya solely because he is allowing others to focus on his other issues; with that said, Oga lands a direct punch to Takamiya's stomach.
Oga gradually begins to tire from their constant fighting; frustrated, he also thinks to himself about how he still cannot grasp Takamiya's individual powers. His exhaustion is easily noticed by Takamiya who then proceeds to explain about the Emblem marked on his hand, revealing that its constant activity does diminish Oga's own strength and those who bear his King's Crest; Oga suddenly remembers Saotome using his own Emblem from the past. Takamiya then states that Oga will need to drain him of his power so that he and his friends can win their battles, adding that Tōjō will especially need it. However, Oga assures them both that Tōjō will be perfectly fine.
Outside, Oga is directed by Takamiya to the courtyards where his classmates and the Himekawa Special Forces are ready to fight; seeing them, he is pleasantly surprised, though he is positive that they will be fine. However, to his shock, he hears Takamiya tell him that he will finally get serious, just as the members of the Himekawa Special Forces all reveal a King's Crest of their own.
Oga and Baby Beel are then suddenly propelled backwards by Lucifer, causing them to fly past the metallic fence bordering the rooftop. Just as they fly past them, the teenage delinquent reaches out for the metal bars, successfully grabbing onto it. He brings himself back to the rooftop while reflecting on the commotion with the "Hime Boys" nearby; back on his feet, he realizes that Lucifer is responsible for the surprise attack, now with a better grasp of her abilities. Suddenly, he is streamed memories of Takamiya's past during his early childhood. Following the series of flashbacks, Oga and Takamiya both deal a powerful punch to one another. Afterwards, Oga berates Takamiya for his depressive nature and states that he will show him that the world is a big place. With a surge of power spiking within him, Oga admits to Takamiya that he hardly understood what his past was about but blatantly calls him off for being a "sulky brat". He suddenly conjures a giant Zebul Emblem in the sky; with the bright light shining down on them, Oga tells Takamiya that he will end the fight just as the latter had wished. Oga takes in several hits from Takamiya, completely to no effect on him, then deals a strong jab to his stomach followed by a powerful kick to the body. He then looks down at his opponent with an intimidating glare.
Suddenly, the Zebul Emblem dissipates and Oga realizes that Baby Beel is no longer with him. As he frantically looks around for the infant, he looks above after hearing a familiar voice, realizing that Himekawa has severed the link between him and his Demon. Oga stares at the two perpetrators with a speechless expression as they explain that he can no longer feel Baby Beel's presence.
Oga then turns to Takamiya who declares that he just wants to beat up Oga; unfazed by the intimidating comment, Oga simply asks what they have done to Baby Beel. Suddenly, Oga coughs up a large amount of blood onto the ground due to using his unique technique just earlier. Afterwards, he is kicked away to the damaged metallic fence bordering the rooftop where he is then struck with a massive amount of Demonic energy, collapsing moments later; Takamiya, however, holds him by the head before he can fall flat on the ground. Oga faintly wonders whether Takamiya is still gaining power before he realizes that his mind is slipping away. He curses out for Baby Beel before he utterly loses consciousness. Unconscious, Oga fails to sense Baby Beel come for him shortly after.
Powers & Abilities
Expert Hand-to-Hand Combatant: Oga, even before meeting Baby Beel, has only used unarmed combat to fight. He uses street brawling and his already inhuman strength to win fights. Now that Beelzebub is with him his strength has been further enhanced with demonic energy. Oga likes to make up crazy names for his attacks even though they're still only regular moves. As with most thugs in the series, he lacks any particular martial art technique in fighting, mostly relying on his natural prowess to diminish the advantage of trained martial artists like Kunieda and Miki. However, he has figured out some classical techniques from wrestling; he outmaneuvered and defeated Tōjō with a German Suplex and leads Baby Beel to do a Clothesline, an Elbow drop, and a Boston Crab to defeat the huge monster they encountered in the Demon World. He is able to hold his own against a Demon for some time without resorting to using Demonic power (although he did use the Zebub Blast against this enemy, it had no effect). He can feel Saotome using his demon power, which shows he has notable strength for a human.
- Street Fighter Techniques:
- Psycho Crusher (regular punch)
- Shouryuuken (regular punch)
- Yoga Chop
- Rocket Punch (regular punch)
- Flash Kick
- Finishing Moves:
- Super Rocket Punch (regular punch)
- Infinity Rocket Punch (regular punch)
- Maou Rocket Punch (regular punch)
- Oga Special Punch (regular punch)
- Demon Punch (regular punch)
Martial Artist: Later, though, upon having to be rescued from a confrontation with a demon by Saotome, he becomes irritated by the fact he is unable to protect anyone and decides to take formal training from Kunieda's grandfather. Oga trained in the Shingetsu style with Kunieda and Kunieda's Grandfather. He showed himself able to learn at a fast pace, splitting stones and even boulders bigger than himself with the Shingetsu's style basic technique: Nadeshiko.
- Shingetsu Style:
- Nadeshiko: Nadeshiko is a technique where the user focuses their power completely on a single spot. This technique is also known as the Armorpiercer.
Spell Master: Originally because of both Oga's inexperience with demon powers and his obsessive search for another parent for Baby Beel, Oga possessed little to no abilities with utilizing a demon's power. He would first display this capability by instinctively using Beel's power in a basic maneuver by channeling the demonic energy and releasing it in an energy blast. After being rescued by Saotome, Oga reluctantly trained under him in the demon arts and after a week the delinquent would expertly use the same technique that Saotome used to drive the Pillar Division demons away. After the arrival of the entire 34th Pillar Division, Oga would train under Suiten Ikaruga in Black Techs to utilize Beel's demon powers.
After this training, Oga became able to easily defeat a Pillar Baron with one move when previously he needed to merge with Beel to defeat a Pillar Baron. Also, Oga displayed better fighting ability against Jabberwock when he previously could do nothing against the general and narrowly defeated the demon. In time Oga subconsciously developed a fatherly relationship with Beel that in turn increased their bond and shared power which is noted by many characters including experienced spell masters that allowed him to defeat the spell masters while his skills remained underdeveloped. Eventually, when his and Beel's relationship is fully developed, Oga was able to fully release Beel's latent powers that allowed him to dominate against a spell master who had merged with a member of the Seven Deadly Sins and had also merged the powers of those who follow him together.
- Zebul Spell (ゼブルスペル, Zeburu superu): The spell on his right hand expands and grows, moving up his arm and spreading across his face. The more it expands the more Oga's power grows. First, when he lost control against Kiriya the Zebul spell temporarily extended up his arm, over his trunk and across his face. After his training with Saotome, he's able to recreate that state through drinking the Super Milk, but his Professor warns him that if it goes any further that, he might not be able to become human anymore.
- Zebul Blast (魔王の咆吼, Zeburu burasuto; Literally meaning "Demon Lord's Roar"): Oga punches his opponent and releases a large amount of demonic energy that's strong enough to destroy a building. After his Ankokubutō training, Oga can use this attack freely without having to wait for his energy to build up.
- Zebul Emblem (魔王の烙印, Zeburu enburemu; Literally meaning "Demon Lord's Burning Seal"): Oga uses the Zebul Spell to target his opponent, then punches it until the enemy explodes from the massive power build up. Through Super Milk Time he can stand on the emblem in mid-air and use its explosion to increase his speed. Oga can also attack with more than one emblem at once when used in conjunction with Super Milk Time.
- Zebul Emblem 3-Hit Combo: An extension of his Zebul Emblem where Oga places three emblems overlapping each other to greatly increased the power of his ordinary Zebul emblem by 3 times.
- Zebul Emblem 5-Hit Combo: This is the same as his Zebul Emblem 3-hit Combo only Oga places five emblems overlapping each other to increase his normal Zebul Emblem by five folds. This can be used in Super Milk Time.
- Black Tech - Zebul Emblem: An enhanced version of his ordinary Zebul Emblem after his Black Techs training where Oga after entering a stronger Super Milk Time he places a larger Zebul Emblem on his opponent and proceeds to give a powerful punch that causes it to explode. This improved version is capable to defeating Basilisk, a Pillar Baron, in one hit whereas Oga needed multiple Zebul Emblems to even harm a Pillar Baron previously.
- Demon Lord's Great Explosion: Oga places multiple Zebul Emblems overlapping one another in a straight line for the opponent and punches the first emblem that creates a chain of powerful explosions which can be used as a booster attack or for distractions as well.
- Zebul Finisher: This is Oga and Beel's ultimate technique where it was first used to defeat Naga, Hecadoth, and Graphel together that involves placing hundreds of Zebul Emblems around the opponent and he proceeds to create a linear chain of Zebul Emblems in front of him that acts as a trigger for an enormous explosion that destroyed the top of a building. It was used when Baby Beel gained complete control over Oga's body from their untrained Super Milk Time. Later on, it was used to defeat the fusion of Fuji and Satan where Oga performs in his normal state and has hundreds of Zebul Emblems placed in front in him like a wall that went above even the Earth's atmosphere. Oga then proceeds to unleash an enormous energy blast this time that stalemated the Fuji/Satan fusion's final attack before overpowering it by placing numerous King's Crest on humans and demons alike that are aligned to him to absorb their power.
- Ankokubutō (暗黒武闘; Literally meaning "Dark Armed Struggle"), also known as Super Milk Time (スーパーミルクタイム, Sūpā miruku taimu): Oga drinks the Super Milk to remove the limiter between Beel and himself, causing them to become synchronized. The Zebul Spell spreads all over Oga's body and he becomes faster, stronger, and takes on Beel's personality. He can also use the Zebul Emblem to a much larger extent. Saotome explains to Oga that he can safely use it for no more than 5 minutes or else he'll lose his humanity and his body will disintegrate. If Oga drinks the whole bottle of super milk, he becomes completely synchronized with Beel. Oga gains wings, darkened skin (in the anime his skin color doesn't change but his hair color turns from brown to green, much like Beel's) and a binky like Beel's appears in his mouth. While synchronized with Beel, Oga gains enough power to easily overpower two demons and injure Saotome's arms when he attempted to guard it. In this state, he looks to be capable of using an apparently infinite number of Zebul Emblems, which he can use to create a huge explosion that can destroy a skyscraper. After his Ankokubutō training, Oga seems to have mastered this state. Due to his training, he became able to control Super Milk Time up to 400cc, shown when he went up from 30cc to 80cc with no apparent side effects. With 30cc he was able to defeat 6 Pillars, and with 80cc he was able to beat the Pillar Baron Basilisk without any injuries.
- Super Croquette Time: This reverses the side effect of Baby Beel's personality, allowing Oga to take control of his (Baby Beel's) enhanced abilities.
- Father Switch (お父さんスイッチ, Otōsan Suicchi): A strange technique that he supposedly receives when Baby Beel is insulted and goes into a so-called "Father's Rage", amplifying his power to the point of being able to defeat Jabberwock. Oga is much more powerful in this state as even when he used Super Milk Time in 400cc and had Tojo's help against Jabberwock, they were easily defeated. This power boost is later proved again when Oga easily defeats Yōhei Nasu using this form even though he couldn't even match him in his regular state. In this form, his eyes become completely empty with no pupils. This was later revealed to be the fusion of the two ways of using a demon's power, Spells (which is the utilizes and controls demon energy) and Ankokubutō (which fuses the body with demon energy). This creates a new type of energy which Saotome referred to as Annihilation Energy. It is done by mashing the two conflicting energies within Oga's body, allowing Oga to use what little demon energy he has left.
- Super Saiyan Switch: A state that Oga achieves when Beel's maximum energy is converted into an electric aura and manifests its power through Oga's body. The increase in power bestowed while in this state is great enough to absolutely dominate Fuji when he was fused with Satan. His abilities were initially too hard to control while in this state because he was too powerful and not conditioned to handle it. Nevertheless, he was able to adapt and learn to fly around in order to defeat the Satan/Fuji Fusion.
- Dispelling: Oga had learned how to dispel another Spell Master's demon spell such Yohei Nasu's immobilization technique, though the Spell Master did say that it was a basic maneuver.
- King's Crest: A technique where if a human places complete loyalty to a Demon Contractor or Spell Master, they will receive a magic brand somewhere on their bodies in the shape of the demon's symbol and lineage, much like the contract symbol for the Contractor or Spell Master. This greatly enhances their power. Later, when Oga performed the Zebul Finisher, he was able to enhance its power by placing King's Crests on humans and demons that are aligned to him. He was able to absorb their powers, rather enhance them.
Immense Strength: Even without his demonic powers, Oga has shown a high level of strength in combat. At several points throughout the story, he is shown to be able to send people flying with his punches and even crush solid stone using his enemies. He's able to end a lot of his fights by shoving, punching, or kicking his opponents' heads through solid concrete walls. He's even shown the ability to easily knock a person out by hitting them in the face with Beel's rattle. He's also able to lift a boulder and Alaindelon with ease, which is both larger than he is. After his Black Tech training, his strength increased even more, to the point where he can easily overpower demons who are not Pillars or higher. He was also able to overpower Jabberwock when he entered Father Switch, though his strength is still far surpassed by Tōjō.
Immense Speed: Oga is shown to be extremely fast, most notably when he was almost able to keep up with a motorcycle going 31 miles per hour, and later when he was able to dodge Aoi Kunieda's attacks at close-range. After his Black Tech training, his speed has increased greatly. Oga is quickly able to take out a group of non-pillar demons, even quickly taking out one who was sniping him in seconds by jumping up the side of a building behind him. In fact, he was so fast that Jabberwock could not even see him move while he was able to keep up with Toujo's supersonic punches easily.
Immense Durability: Oga has consistently shown himself able to take a great deal of punishment and still be able to continue fighting. For instance, Oga has strong endured melee attacks from the likes of Tōjō and Aoi and continued to fight with little effects on his performance. Oga was able to endure a direct punch from Tōjō without getting knocked out or injured(the first person to resist a punch from the Tōhōshinki member), even though he was sent flying dozens of meters away.
- High Electricity Tolerance: Due to being shocked by Beel numerous times, he has grown a sort of immunity towards electricity, as shown when he was able to block Himekawa's stun baton (which was 12,000,000 volts) with no injuries, despite the fact that the stun baton was said to be powerful enough to incapacitate a grown adult for three days.
Oga and Beel share a unique relationship as Oga's personality would seem to contrast with his role as a parent. Oga spends much of the first arc trying to pass Be'el on to someone stronger and more evil than him, resenting his current role as a parent to the future demon lord.
After Be'el is taken by Toujou, Oga admits that he still doesn't want to look after him, but accepts that Be'el wants him to be his parent. After all the time they spent together, they've formed a close bond, and Oga seems to act more friendly towards Beel. They've gotten close enough that Oga can understand Beel's way of speaking. Oga, even if he is not interested in the fate of humanity, states that he won't let Beel destroy it because all this is stupid and since he is his parent. He says Beel will not do something so useless, indicating that Oga truly accepts being Beel's father. Every time Beel cries, he sends out an electric shock. However, at the end of the final episode of the anime, Beel cried without shocking Oga for the first time.
Furuichi is Oga's best and, at the beginning of the series, only friend (quite possibly because he was the only one willing to put up with Oga and his antics). Because of the differences in their personalities, the two spend a considerable amount of their free time arguing. However, in a dangerous situation, they band together and work well together. Oga is frequently willing to do things at Furuichi's expense, often thinking that Furuichi himself won't mind. In a recurring theme, mostly used for comic effect, that they are able to communicate without saying anything aloud, showing their close bond and a great understanding of each other.
Their past along with the strength of their friendship is revealed in the Tissue Arc. They became friends when Furuichi constantly tried to get to know Oga, eventually, Furuichi fought with Oga and told him that he would stand beside him and not behind (this was because Oga could not protect him easily from behind) whenever Oga was in a fight. Oga claims that Furuichi is strong enough without the use of demonic powers and shows some respect for him, asking the Redtails to stop calling him a 'lolicon'. Oga does worry for Furuichi, expressing worry when Behemoth granted Furuichi power and later playfully kicking and berating Furuichi for worrying him.
In the most current arc, when Furuichi was kidnapped, even after being told by Saotome that he shouldn't fight Fuji or Takamiya, as they were "worlds apart in skill", Oga simply stated that he didn't care about that and went anyway, presumably for Furuichi. After seeing Furuichi and the six pillars beaten by Takamiya, Oga fights him. Unfortunately, in an attempt to make Oga stronger so he can have more of a challenge, Takamiya has his demon Lucifer take Furuichi's soul (heart) and breaks it into six pieces.
Oga's relationship with Hilda is one of the most complex relationships of the series. She often looks down on him and never hesitates to mock him. In turn, he finds her cold and manipulative personality annoying. However, it is shown on rare occasions that they do care about each other, such as when Hilda thanks him for helping her get Beel back from Tōjō, and when Oga became enraged at Hecadoth for harming her. It should be noted that the two work extremely well together in a fight. They are also known as 'The Most Evil Couple' and 'The Strongest Husband and Wife'.Hilda is already considered as Oga's apparent bride/wife by the whole Ishiyama school and his family, thus gaining her nicknames such as "Oga's bride", "Wife", or "Wifey". The two don't bother to correct other people's opinions, considering it to be a waste of effort to explain. As the chapters pass by, their relationship has grown in leaps and bounds. Oga's family has accepted Hilda's presence as a family member, especially his sister Misaki. Although they still constantly bicker, it's clear that Hilda respects Oga and vice versa. Oga still eats the food that Hilda makes, even though it's usually too disgusting or spicy. A pinnacle point in their relationship occurs when Oga saves her from being kidnapped by Jabberwock. Realizing that Oga's tactics wouldn't stop Jabberwock, she pulls Oga close and tells him that she is leaving Beel in his care alone, giving him a rare sincere smile. She then allows herself to be taken by Jabberwock's dragon in order to save Oga and Beel. Her parting words were, "You're...the only father he has in this world", implying she has finally accepted Oga as Beel's parent. Oga, on the other hand, goes as far as to breaking into Akumano Academy alone in order to rescue her.
When Oga arrived at Akumano Academy, he received a very loud scolding from Hilda. She said that he was endangering Beel again, and that he was being very reckless and stupid. But Oga shouted back, at the same volume, that he came all that way just to save her, adding that that she should shut her mouth and wait for him. Surprised, Hilda's eyes widened and she stayed silent.As the battle between Jabberwock and Oga unfolds, Oga makes Hilda's rescue his top priority. Being impatient, Jabberwock surprises them with a beam of demon power aiming towards the crucified and almost unconscious Hilda. Oga moves quickly to get Hilda before getting hit by the blast. The barely awake Hilda caresses Beel's cheeks and told him how glad she was that he was safe before falling completely unconscious. Jabberwock laughed and commented on how stupid she was. Oga became filled with anger and told him to not laugh at her. He attacked Jabberwock due to him mocking her loyalty toward Baby Beel.
By the time the Akumano Academy arc ends, his care for her has grown even more, admitting that he can't bring himself to tell the amnesiac Hilda the truth about their situation, simply because he saw how happy she was. He does become more shy when people says that Hilda is his wife, however, and is completely freaked out at the way the "new" Hilda acts toward him (caring and loving like a real wife and mother-of-his-child, even sleeping in the same bed as him).
As time passes, he gradually becomes more fond of Hilda, while trying to help her regain her memories. In the end Oga accepts "new" Hilda, saying that regardless of which personality she has, it doesn't changes the fact that she is Beel's mother. He says that he actually enjoyed her food. She is one of few people, along with his own family, that he allows to call him by his first name, "Tatsumi". In the end, however, Hilda regained her memories right when Oga said that the original Hilda's cooking skills were practically "attempted murder". She promptly threatened him, saying that next time wouldn't be attempted murder, and beat the living daylights out of him. It should be noted that she still occasionally calls Oga "Tatsumi" even after turning back to normal. When the two are alone, Oga shows a much softer side to Hilda that not everyone sees, even Furuichi.
Out of all the characters in the series, Oga treats Kunieda the nicest. Oga first meets Kunieda in the park for his park debut (She was in disguise). After failing to make any progress for his park debut he sees Aoi laughing when Oga is called a murderer so he approaches her and puts his hands on her shoulders and asks Kunieda to go out with him. At first, she is shocked and thinks that he is to asking her to go out on a date. Only to realize a while later that he actually meant to help him out with his park debut.
When she arrives at school alongside Nene and Chiaki she searches for him assuming that he is a bad guy that had caused so much violence and so many people to be hospitalized. So to prevent Ishiyama from being destroyed by him she picks a fight with him. Kunieda catches his attention due to her display of her strength. He hands over Beel to her after their second confrontation, but Kunieda declines and believes that Oga is the father of Beel. Oga explains to her that he is not his father but he is forced to raise him .
He is nicer to her when she is in disguise (Aoi Kunie) such as buying her ice cream when they meet again in the mountains. Due to his dense personality, Oga fails to realize that Aoi Kunieda and Aoi Kunie are the same person, falsely implying the two are cousins. As the series progresses, Kunieda starts to show more interest in Oga, such as asking for his phone number so she has a way to contact him. She slowly grows feelings for Oga, which he fails to notice due to how dense he is.
Oga and Tōjō have a 'frenemy' relationship. They don't mind competitively fighting against each other just to know who's stronger, but they're still able to communicate and joke with each other like friends. In a twisted way, they enjoy fighting each other, a good example is when after Oga was beaten down by Miki, he went to Tōjō and asked him to a fight. As they were pounding each other, they started laughing and enjoying themselves. Since the Tōhōshinki Arc, the two have developed a decent friendship with one another.
Oga, Furuichi, and Miki were friends during middle school. Oga met Miki when Miki was getting beaten up by thugs until Oga came by and rescued him. During Miki's last day at middle school with Oga, in a same time he learned that Kiriya is also about to move to Nara as Miki, Oga pretended not to know Miki beaten him in front of everybody and Miki resented Oga ever since. However, after learning the truth, Miki then realized that Oga never had forgotten about him. After the incident with Teimō, Miki has tried to tighten up their friendship again.
Yamamura admires Oga greatly and wants to be his disciple. Yamamura praises him deeply and calls him "bro", which Oga finds to be flattering, despite not initially having wanted Yamamura as his disciple.
Jabberwock immediately dismisses Oga as an unworthy opponent on first meeting him, but he develops a small amount of respect for him after they fought for the first time. When he faces Oga a second time, he sees Oga as a worthy opponent and happily battles him and Tōjō. During the battle, he was proud of Oga's strength and wore a smile through the battle. At the end, he said it was fun.
- "Bow to me!!" (his catchphrase)
- "Doskoi." (to Aiba)
- "Men are fighting spirit." (to Furuichi)
- "Men... don't freak out crying. You'll be made fun of." (to Beel)
- "... I don't want it either." (referring to Beel)
- "What the hell do you think you're doing? You cut our link to protect me?! Who the hell do you think you are? Your electric attacks... are nothing more than a little static electricity to me!" (to Beel)
- "Neither. I fight just for me. First off... that brat's not even mine. It's the exact same thing as you; I picked him up and took care of him that's all. Whether he comes back to my place or stays stuck to you, thats... up to him." (to Toujo referring to Beel)
- "It's time to eat!!" (to Beel)
- "Just playing upsydaisy is life threatening" (to Beel)
- "Trash, goes in the trash can." (to a police officer)
- "Is this...what they call a park debut...!?"
- "Let me tell you something good... Beel won't destroy the human world, Do you know why? It's because I'm his parent, I won't ever let him do something this stupid." (Oga to Naga)
- "Idiots are not good!"
- "I'm here to rescue you, Dumbass! So shut up and wait for Me!!" (to Hilda)
- "This doesn't even hurt compared to when baby Be'el cries at night." (to Himekawa)
- "Bring it!" (to Jabberwock)
- "Don't you dare laugh at her!" (to Jabberwock referring to Hilda)
- "Where the Hell do you get off saying that? Worms are living beings too." (to En after hitting him on the head)
- "Regardless of what personality you have, it doesn't change the fact that you're his mother." (to Hilda)
- "She's in a bitchy mood." (to Beel, referring to Hilda)
- "And this is why you're known as 'Creepichi'." (to Furuichi)
- "You`re damn strong already, even if you`re not using those." (to Furuichi)
- "You can't catch crayfish in the winter. They go into hibernation." (referring to the Pillars)
- "Damn that Furuichi. He let the cat out of the bag! When I find him, he'll experience a fate worse than death!" (referring to Furuichi while hiding in the bushes)
- "Huh? It went beyond the point of bad. It was attempted murder! It was like a new chemical weapon." (to Hilda, referring to her cooking)
- "Now then, let me teach you something. THE WORLD IS A BIG PLACE!" (to Takamiya).
- The first part of his first name, Tatsu, means Dragon. This is a play on the Eastern mythology of the Tiger and the Dragon, in which Oga is the Dragon and Hidetora Tōjō (Tora) is the Tiger.
- When Oga switched bodies with Beel, he stated that he wanted to play the piano.
- Oga's perfect impression of himself is like a boy in a shōjo manga while holding a glass of wine.
- While Oga's hair is portrayed as dark brown in the anime and manga, some manga chapters depict it as being a lighter brown.