Tatsumi Oga

"Oga" redirects here. For other uses, see Oga (disambiguation).

is the main protagonist in the Beelzebub series.

Oga is first introduced as a strong fighter, beating up some fellow class mates and then making them bow down to him because they had attacked him in his sleep. He was picked to become Beelzebub's father because he possessed the qualities of the ideal parent for the future Demon King: strong, arrogant, and thinks-nothing-of-fellow-man. In addition to the aformentioned attributes, Oga also seems to take pleasure in tormenting others. Oga and Beelzebub cannot be separated by more than 15 meters or else it may result in instant death for Oga, according to Hilda [2] (as of chapter 38, the distance has increased with 8 centimeters).

Appearance
Oga is usually seen sporting a grotesque grin and his demonic features are visibly shown when he is either angry or disturbed. He possesses brown hair and dark eyes, he is rather muscular with a wide-spread build, and his attire usually consists of a worn-out shirt and plain pants (usually jeans). He has been shown on a few ocassions to be wearing either sweatpants, and on one ocassion, has even been shown wearing his pijamas (ironically very 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. Be'el does not transfer this emotion however, and is usually shown in a maintained angry look.

Personality
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, reguarly resulting to cruel and unusual methods of punishment for his defeated enemies. It is because of these qualites that he was initially chosen to become Beel's parent. The qualites apparently needed were, "Strong, Tough, Self-centered, and cares nothing for his fellow man" as "that kind of shitty bastard is the best."

As the series continues, it should be noted that the trials Oga has faced and the new friends he has gained has altered his personality somewhat. For ex; When the Horsemen called out Ishiyama to meet them on the rooftop, Oga first came alone. But later on Himekawa, Kunieda, and Natsumi soon arrived and Oga smiled knowing that they have his back. Though he retains his love for his cruelty, he is now much more calm and easier to be around then he was at the start of the series.

In his own twisted way, he seems to care for the people that are close to him. When Furuichi was gone during for summer vacation and leaving Oga alone, he called Alaindelon to transport Furuichi back home just so he can hang out with him. Or beating up and embarassing Miki infront of their school back in middle school. Only because it was to protect him from Kiriya Reiji because he knew that both Miki and Kiriya would move to Nara at the same time, and if Miki was involved, then Kiriya would've attacked Miki in Nara where Oga wouldn't be there to protect him.

Oga doesn't seem to have any sense of appeal nor opposition against girls, unlike Furuichi who is easily seduced and will not hesitate to pick up girls. However, he does also has a sense of chivalry, as said by Hilda, Oga will not fight or harm a woman.

As much as Oga hates it, he tends to listens to lectures very well. For ex. When Oga was telling Teimou about Baby Beel's demon praying dance, Kunieda quickly takes him to the side and lectures him about being careful who to talk to about demons and only talk about them who are involved. After that, Oga never told anyone besides (excluding demons) Furichi, Kunieda, Kunieda's Grandpa, and Saotome. Or when Saotome was lecturing Oga about using Super Milk Time for 5 minutes max. When Oga uses Super Milk Time, he only fought for 5 minutes after using a huge blast that knocked him into unconsciousness.

Ishiyama High Arc
The series began in a light-hearted fashion (common with most shonen mangas including Katekyo Hitman Reborn and One Piece). Oga was introduced destroying armed mercenaries and local thugs. As they pleaded for mercy Oga fought them alone, 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 came floating upstream (the local riverside) and he eventually cracked open, revealing a small baby. Furuichi is shocked by Oga's lack of story-telling abilities (although the retelling was revealed to be true), and the two continue in loud voices. Be'el is completely focused on the conversation at hand and he remained quiet for the most part of their conversation. Oga continues his rant on the Be'el situation and reveals that he must take care of the demon baby, because the child is so attached to Oga's raw abilities. Hilda is mentioned and referenced during his conversation and Furuichi is quite taken by her.

The next day, Oga takes Be'el to school with him. Furuichi wonders out loud why he would go to 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 Be'el and are shocked by their self-perscribed 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 Kansaki in an attempt to force Be'el on him. His logic was that "strong men" were most appealing to Be'el, 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). Be'el was touched on the head by kanzaki, Oga realized that he was rejected as Be'el 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 afterwards, Himekawa went to handle Oga directly. He kidnapped Furuichi and Hilda (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 had the two held. He blasted through his thugs (reinforcement), and made his way to Himekawa. However, Himekawa turned out to be a more competent opponent than Kanzaki. His weapon was a stung rod and 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 Be'el's tantrums. With Be'el'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 Tohoshinki, 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 Be'el to the park as what he calls his park debut. There he meets a young girl wearing glasses and a stroller. 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 Tohoshinki, the leader of the feminine group Aoi Kunieda. Although she wears a disguise at the park, perhaps 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 Be'el 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. Oga is quick to the challenge and avoids fighting her. Aoi is shocked to see that Oga is carrying a child, and as such is thrown completely off guard by him asking her to become Be'els mother. Although it was merely his means to ditch the child, Aoi took this as more of an invitation to become his partner, and as such, she became infatuated with him even developing a crush along the way.

Oga's troubled road through Ishyama continued when the last and final Tohoshinki was revealed. Oga left his house after Be'el showed signs of their severed bonds. He was launched out of his window after showing a hurt and emotional Hilda his theory of leaving Be'el. 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 alley-way. Their fight was only a means of testing Oga's power, and as such, the subbordiante left without any signs of anger or tiredness, a statistic Oga picked up on well. A confused Oga wondered about the the relation the two shared. The subordinate answered calmly and then exited the alley-way, missing his next hit on Oga (which was sure to be a devastating blow).

When Oga awoke the next morning, he noticed baby Be'el was missing and Hilda was once again absent. Furuichi pondered this and spoke openly on why Oga was taking the situation to 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 Be'el. Tojo and his subbordinate were there, and Be'el was also present, this time riding on the back of Tojo. A fight ensued, and with that Oga began to notice issues with Be'el. HIs glazed eyes were unfocused and the attachment to Tojo was almost abnormal. Oga concluded that the power he had was enough to draw Be'el towards him. Oga demanded to know how he found Be'el in the first place. Tojo answered honestly that he found Be'el roaming the streets. He then took a few jabs at Oga's terrible parenting skills. Be'el was set to be the prize of the fight, and Oga was quickly beat to the point where he succumed to serious injuries. Oga took the upper hand, catching him of guard until he noticed the zebub spell's contract on Tojo's arm. Tojo sent Oga flying and afterwards took Be'el 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 who Hilda called to assist with the examination of Oga and Be'el. 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 Be'el. A bruised Oga relinquished his role as surrogate father momentarily, in an attempt to regain his strength. Oga wondered aloud whether Be'el was better off with Tojo. He was snapped back into reality by Hilda and his fighting spirit 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 Tojo. Tojo defeated Kanzaki and Hajime with help from his own subordinate, a bespeckled man with apparent power. Kanzaki and Hajime are forced to work with Oga in an attempt to defeat Tojo. 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 female group is also present and Aoi tells Oga to continue on ahead and find Tojo.



Oga runs into the school looking for Tojo. On his way, he notices fireworks being set off, and he continues on his way towards the fireworks' location. When the two meet, Tojo reveals he figured out that Oga's the father of Be'el. He inquires to return it, stating that perhaps a fight over him would be more suitable. Oga states his relation to Be'el being more caring and out of friendship, then going to say that it is up to Be'el to decide. The once warped Be'el regains his composure and glazed look, and he creates a demon circle with estranged markings. A force-field is created and the electric prevents anyone from entering. Oga penetrates the sheild, doing more damage to himself, and with a cocky smile gives Be'el the same 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 Tojo. The fight between the two was full of complacent blows and rigorious hits. Oga had Tojo 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 Be'el and Furuichi's location (Furuichi being there on his own accord). Be'el feeds Oga some power, and the contracting Zebub spell is generated. Oga tells Be'el to stay away from the fight, this includes his help with any zebub spell or magic of any kind. Be'el realizes this, and he sinks his power back to himself. Oga continues his fight and takes a blow from Tojo on purpose, as a means to get bind him and engage a suplex-type move, crushing Tojo.

An exhausted Oga limbers back to Be'el stating his win and the two lock eyes. Oga then notices that his arm deformed during the fight. The magic built up and released explictly through his arm. The blast destroyed the school and the trials at Ishiyama High concluded with Oga reighning victory over the Tohoshinki.

Saint Ishiyama High Arc
Because Oga destroyed Ishiyama, a vast majority of the deliquents from Ishiyama were relocated to its sister school, Saint Ishiyama Academy. The people relocated included Oga, Furuichi, the Tohoshinki, their subordinates, and the MK5. The group was relocated for the time-being as there were no other alternatives, but 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 part 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. 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", quoting that he was "moving up in the world".

Later after a fight with a rival school, Oga and Aoi, who were 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 being 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 Knights: Miki, Sakaki, Ichiro and Hiromichi. At first, Oga stated that he would fight all of them. He was joined by Tatsuya, Aoi and Shinataro. Each began their own fight while Oga defeated Ichiro with one punch. Afterwards 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.Toujou arrives to fight and withstands Miki's attack to fight Izuma but is dissuated 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, initally 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 Toujou 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 Be'el 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's power. At the end of the festival, Ishiyama is accepted as part of the school.

Prince En Arc
After the 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 remebering 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 Zenjuro 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 Zenjuro's energy as he closes the the wormhole Oga made during the festival. Feeling the energy, he travels to the gym as Zenjuro is leaving after restraining Hilda as Zenjuro leaves he tells Oga to come to school tomorrow. He is then confronted by Kuineda about who baby Be'el is; as he tries to explain, he hurts baby Be'el's feeling because he dosen't remember his full name. As baby Be'el 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 who calls himself En appears as he names himself baby Be'el's brother, but before he says more they move to Furuichi's house. After explaning his purpose to destroy the world with Be'el, En and his wet nurses soon disappear after explaning that some En's men will come for Oga's life. As Oga, Hilda, and Kuineda head home, a moment of silence came. When the time that Kunieda must part ways because her home was the other way, 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 Kunieda. The plan went just as planned, but the demon read their tactics. Hilda got pierced with the spear of the demon, right through her stomach. Falling helplessly on the road, baby Be'el 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 Be'el. Enranged because of what happened, Oga fought the demon even though it 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 inadvertantly fell asleep. After being defeated easily, Oga takes up Kuineda's grandfather's offer for training. After compelting the training, he then started training with Zenjuro; fighting a copy of baby Be'el 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 was invented accidentally during his training with Zenjuro. Hilda realizes that he had "forced a synchro", or synchronised himself and Baby Be'el. After a while, he drinks a bit more milk, causing a complete synchronization, uniting himself and Baby Be'el into one body. However, with Be'el, 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 and Furuichi's misunderstood act of guarding Lamia from the falling ceiling, declaring that he would be back one day with a whole army to crush them. Oga is seen unconcious with Beel at his side.

Akumano Academy Arc
After the fight with Behemoth's fellow, Oga and and Beel faint. When they woke up they exchange their bodies, so Oga is stucked in Beel's 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 hugsr and stays close to her, and because of this, Hilda gets jealous. The two Women figt on the roof, but this Time, Aoi is stronger after her training, and beating her is not a simple task for Hilda. Suddenly, Beel-Oga hugs Aoi and she blushes; Hilda gets even more pissed, and Oga-Beel also wants to stop Beel-Oga. The 3 attacck Beel-Oga at the same time, but in that instant, Oga returns to his own body, resulting in Him beeing 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 Grandpa Ittousai Kunieda, he reveals to have rebuilt the Ishiyama High and renames it as Akumano Academy, a school of demons.

Fighting Style
Oga, even before meeting Baby Beel, has only used his fists to fight. He uses street fighting techniques and his already inhuman strength to win fights. He also knows a lot of wrestling moves like the "German Suplex" and "Boston Crab." 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.(Professional wrestling attacks)

As most thugs in the series, he lacks any particular 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 defeats Toujou with a suplex and leads baby Beel in a Clothesline, an Elbow drop, and a Boston crab.

He is able to hold his own against a demon for some time without resort to demon 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. 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.

More recently, Oga is training in the Shingetsu style with Kunieda and Kunieda's Grandfather. He has shown to learn at a fast pace, splitting stones and even boulders bigger than himself with the Shingetsu's style basic technique: Nadeshiko. Nadeshiko is a technique were the user focus his or her power completely on a single spot. This techinque is also known as the Armorpiercer. Other Traits:
 * Zebub Spell - 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. In chapter 75, the Zebub spell temporarily extends up his arm, over his trunk and across his face. Saotome warns him that if it goes any further that he might not be able to become human anymore.
 * Zebub Blast - Oga punches his opponent and releases a large amount of demonic energy that's strong enough to destroy a building.
 * Zebub Emblem - Oga uses the Zebub 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 it's explosion to increase his speed. Oga can also attack with more than one emblem at once when used in conjunction with Super Milk Time.
 * Super Milk Time - Whe Oga drinks the Super Milk, he removes the limiter between Beel and himself, causing them to become synchronized. The Zebub spell spreads all over Oga's body and he becomes faster, stronger, and takes on Beel's personality. He can also use the Zebub Emblem to a much larger extent. Saotome says Oga can only use it for 5 minutes or else he'll become a demon permanently. If Oga drinks the whole bottle of super milk and becomes completely synchronized with Beel. Oga gains wings, darkened skin, and a binky like Beel's in this state. 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 appereantly infinite number of Zebul Emblems, which he can use to create a huge explosion that can destroy a skyscreaper.
 * Unnatural Strength - Even without his demon 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 also able to lift a boulder and Alaindeon which are both larger than he is.
 * Unnatural Speed - Oga is shown to be extremely fast, most notably when he was almost able to keep up with a motorcycle going 50 kilometers per hour, and later when he was able to dodge Aoi Kunieda's attacks at close range.
 * 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 rod with no negative effect.

Beelzebub
Oga and Be'el 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 his parent. After all the time they spent together, they've formed a close bond, and Oga seems to act more friendly towards Be'el. They've gotten close enough that Oga can understand Be'el's way of speaking. In chapter 107 Oga states that he won't let Beel destroy humanity because "he is his parent," indicating he truely accepts being his father.

Furuichi Takayuki
Furuichi is Oga's best and, in 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. It is a reacurring theme, mostly used for comic effect, that they are able to communicate without saying anything aloud, showing their close bond and great understanding of each other.

Hildegarde
One of the most complex relationships of the series, he and Hilda share a love-hate relationship, most often bordering on the hate side. Hilda 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 Toujou and when Oga became enraged at Hecatos for harming her. It's quite concievable, though, that maybe they feel something more for each other. It should be noted that the two work extremely well together in a fight. Even the other wet nurses have pointed out that being around Oga has changed Hilda, a proof of their invisible yet strong relationship.

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 nick name, "Oga'sbride/Wife/Wifey". Both of them (Hilda and Oga) doesn't really bother to correct other peoples opinions, considering it's a waste of effort to explain. As the chapters past by, Hilda's and Oga's relationship have grew in leaps and bounds naturally, even Oga's family have accepted her presence as a family member, specially his sister Misaki. Although their constant bickering are still present, Hilda gained Oga's utmost respect and also vice-versa. Hilda is possibly the closest girl to Oga in the series (excluding his family).

Kunieda Aoi
Oga first met Kunieda at the park for his park debut. (She was in disguise). During the time, Oga asked Kundieda to go out with him. At first, she thought that it was to ask her out on a date. Only to realized that he meant to help him out with his park debut. Early in the series, Oga wanted to give Baby Beel to someone that is stronger. Kunieda caught his attention and wanted to give Beel to her, but Kunieda believes that Oga is trying to advance with her and thought it was love. He is nicer to her when she is in disguise (Kunie Aoi) such as helping her and buying her ice cream, probably because Oga has a fresher view on Kunie Aoi than Kunieda Aoi, the fact that when they first met in school, she immediately starts a fight with him. Due to his dense personality, he fails to realize that Kunieda has a crush on him and that she and Kunie Aoi are the same person. Out of all the characters in the series, he is nicer to Kunieda than anybody else. He never shows any animosity towards her, never calls her names and doesn't argue with her. He also seems to care about her when she got kidnapped by a demon.

Toujou Hidetora
Oga and Toujou has a Friendemy relationship. They don't mind competively fight against each other to know who gets stronger. But 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 Toujou and asked him to a fight. As they were pounding each other, they were laughing and enjoying it.

Miki Hisaya
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 last day at middle school with Oga, Oga pretended not to know Miki beaten him infront 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 Teimou, he and Miki tried to tighten up their friendship again.

Yamamura Kazuya
Yamamura admires Oga greatly and wants to be his disciple.

Quotes

 * "Bow to me." (his catchphrase)
 * "Men are fighting spirit." (to Furuichi)


 * "Men... don't freak out crying. You'll be made fun of." (to Be'el)


 * "...I don't want it either." (refering to Be'el)


 * "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 Be'el)
 * "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 refering to Be'el) 
 * "IT'S TIME TO EAT!!" (to Be'el)
 * "Let me tell you something good... Beel won't destroy the human world, Do you know why? It's because I'm his parent." (Oga to Naga)

Trivia

 * 1) The first part of his first name, Tatsu, means Dragon. This is a play off the eastern mythology of the Tiger and the Dragon, in which Oga is the Dragon and Tojou Hidetora (Tora) is the Tiger