Tōhōshinki Arc

The first story arc in the Beelzebub series. The Tōhōshinki arc consists of Chapters 1-40 in the Manga and Episodes 1-22 in the Anime, and introduces the main characters and several other supporting characters. The arc also details Tatsumi Oga becoming the adoptive father of Beelzebub IV, the son of the Great Demon Lord sent to the Human world in order to destroy humanity.

Synopsis
Spoiler warning: Plot and/or ending details follow.

Introduction
A young delinquent teenager, Tatsumi Oga, is sitting in the bedroom of, and with, his best friend Takayuki Furuichi while trying to tell a story. There is initially an interruption with the story-telling after Furuichi suspects that Oga is trying to fabricate some of the plots, resulting in a brief scuffle between the two, but Oga then continues to tell his story.

In a flashback, it shows Oga having finished beating up a group of teenagers and then asking them to bow before him. They oblige and then ask for forgiveness, apologizing for having attempted murder on Oga while the latter was sleeping. Oga brushes off their pleas and proceeds to drown one of them in the nearby river (claiming he was doing some "laundry"), before noticing a muscular man float down the river. Oga pulls the man ashore and the latter suddenly splits into two, revealing a green-haired baby. Oga thinks of options he can do about the current situation and tries to help the baby, twice, to no avail. After putting on an evilish face, the baby suddenly becomes attached to Oga.

It is then revealed that the baby is still with Oga in the present timeline, having followed the delinquent. Suddenly, a woman dressed in elegant Gothic clothing enters the bedroom through the window by riding her Ak-Baba. She demands that Oga hand the baby to her, to which he denies, creating an argument between the two. The baby suddenly sends off an electric shock after listening to the two argue, causing the woman to apologize and officially introduce herself and the baby: the baby is a Demon Lord named Kaiser de Emperana Beelzebub IV and she is his Demon Maid, a wet nurse named Hilda.

Hilda then proceeds to give Oga and Furuichi a better explanation of the situation. Beelzebub (also known as Baby Beel) was sent by his father, the Great Demon Lord, to the Human world in order to destroy humanity. His father was originally supposed to do the destruction himself but do to his busy schedule, sent his son instead.

Oga is then told that he must take responsibilities for his actions, as Beel is now seemingly attached to the Human delinquent. He denies to become a parent and Hilda, realizing that he won't live up to his duties, tries to kill him and Furuichi. This causes a massive explosion in the house, resulting Oga and Furuichi to run away for safety. Hilda catches up to them, however, and from the angled distance between the three Furuichi then comments how he can see up Hilda's skirt, provoking her and causing her to get Aka-Baba to attack them.

Eventually, the three come across an overhead power-line where a group of teenagers recognize Oga from Ishiyama High School. Meanwhile, Hilda cuts Oga's cheek with the sword hidden under her parasol and the blood falls upon Beel's cheek. The teenagers realize that Hilda is attempting to kill Oga and are thrilled by the news. They then try to assist Hilda in hopes of gaining popularity. Beel starts crying, however, and electrocutes everyone including the teenagers. His cry is enough to even send Hilda flying back when she attempts to calm him down. When things begin to turn sour Oga simply places a hand over Beel's head and calms the latter down, then turning to walk around. A steel tower begins to fall over Beel however and Oga protects the baby. However, he then passes out.

The next day, Oga wakes up and thinks that everything was a dream. Much to his shock, it was actually real: Hilda and Beel are sitting in his room, the former stating that Be'el will become a great Human-destroying Demon Lord.

Becoming the Demon Lord's Parent
Hilda, using her real name Hildegarde instead, introduces herself and Beel to Oga's family, orchestrating a scene that makes it appear that Oga had impregnated her and became a father. While Oga refuses to take responsibility for a child he doesn't truly father, his family forces him to become a man and accept his parental duties (unaware of the actual truth). Eventually, the other delinquents at Ishiyama High School learn about Oga raising a young baby, Beel. This is because that now that Oga is Beel's parent, he cannot be more than 15 meters away from the Demon infant or else he'll die.

Oga soon finds himself reaching his breaking point and while discussing it with Furuichi, unexpectedly meets the "man who split into two at the river". The man is revealed to be Alaindelon, a Transdimensional Demon. Oga is angry at Alaindelon as he's responsible for burdening him with so many responsibilities but Alaindelon tries to explain himself. He states that the ideal parent of the future Demon Lord is tough, arrogant, sadistic, and brutal; these are all traits that highly define Oga. Oga then suddenly comes up with a plan to free himself from his troubles: find someone who can be a better parent for Be'el. He states that the plan will succeed as Ishiyama High is a school populated by delinquents.

Going forward with his plan, Oga then goes to meet a strong delinquent named Hajime Kanzaki in hopes that the third-year student would prove capable of raising Beel. When Oga tries to explain things in a more understandable manner, Furuichi steps in and proclaims that he and Oga wish to serve under Kanzaki. Kanzaki obliges but only if they're able to defeat Takeshi Shiroyama, one of his most loyal subordinates. Oga quickly defeats Shiroyama and is granted permission to join Kanzaki's gang. Shiroyama, however, struggles to get up and claims that he can still fight. Kanzaki kicks him, saying that he has no use for the underling anymore, but Shiroyama continues to state that he can still fight. Having had enough, Kanzaki asks him to jump from an open window in the room but gets Oga to do it when Shiroyama apparently can't do so. However, Oga notices that Kanzaki isn't strong enough to become Beel's parent and punches the third-year instead, sending him falling out of the window. Kanzaki is soon brought to a hospital by an ambulance.

Later during a rainy day, Oga awakens and soon learns from Hilda that Beel is having his "blessed" annual urination, in which Beel urinates clean water enough to sink an entire town. Beel's constant urination soon becomes a problem and Oga tries solving it by getting him a diaper. While at the store, one of the employees find Oga and offer to get him diapers after recognizing the latter. The employee is Shintarō Natsume, one of Kanzaki's underlings. Natsume is impressed by Oga's abilities and comments how easily he defeated Hajime Kanzaki of the Tōhōshinki, though Oga doesn't understand what Natsume is saying, let alone know the delinquent. Hilda, who'd been standing in the store aisle, unsheathes the sword in her parasol and attempts to kill Oga after he seemingly fails to understand his responsibilities. She misses, however, and almost strikes Beel. Oga catches Beel before the latter can get injured (from falling on the ground too hard). After witnessing the act, Hilda decides to help and let Beel urinate on the ocean.

When Oga goes to school the next day, he notices an unusual tattoo on his right hand. Hilda and Alaindelon, who followed him to the school, also notice the tattoo and explain it to him (and Furuichi) on the school rooftop. The mark on Oga's hand is the Zebul Spell, also known as the Crest of the Royal Family. Suddenly, Furuichi asks why a Demon Lord needs a parent if another Demon (i.e. Hilda) is already present to raise him. Alaindelon then explains that Beel can only use his Demon magic with someone to help him utilize it, comparing his situation to how electricity needs to run on power lines. Therefore, there comes the need of a Human parent as they can fully access the Demon Lord's powers. Later on, the five decide to go to a pier. Alaindelon and Hilda talk about Oga and the Zebul Spell while Oga, Furuichi, and Beel fish. As they fish, Oga makes a deal with Beel: if Beel doesn't cry anymore, he won't fight for whatever reason anymore.

Meanwhile, a young delinquent named Tatsuya Himekawa is given a picture of Hilda (taken from earlier that day) and he sends a group, Team Caras, out to capture and bring her to him. The group finds Oga but the latter escapes by swimming from the pier along with Beel, having taken his vow seriously. Furuichi, now alone, is asked for Hilda's phone number by the delinquents but states that he doesn't know it, let alone whether Hilda actually has a phone. He then tries to escape through non-violence but one of the delinquents punches him, causing Hilda to come over. Before he can react, Furuichi is knocked unconscious and awakens in an abandoned warehouse along with Hilda, also unconscious.

Furuichi then notices the delinquents from earlier and one of them, the same one who knocked him out, pulls out a gun and points it at Furuichi. Himekawa then appears, however, noting that Hilda is very attractive. He also notices Furuichi and asks why he's there, to which he is told that the first-year is a friend of Oga's. Himekawa beats the delinquent and asks the now-awakened Hilda for her phone so that he can call Oga, but she responds that she doesn't know what he's talking about. Himekawa pulls out a gun, one that ejects burning liquid, and shoots at her, burning off parts of her clothes. Furuichi then offers his phone, wanting to help Hilda and himself, to which Himekawa obliges and uses to call Oga. He tells Oga to meet at his current location if Oga wants Hilda and Furuichi safe. As time passes, it appears as though Oga isn't coming though Furuichi denies it.

Suddenly, the members of Team Caras capture Alaindelon whom they note was unexpectedly weak. Alaindelon splits into two, however, revealing Oga and Beel hidden inside him. Furuichi wonders if Oga's forgotten his vow, but Oga contradicts that he's not technically fighting anymore: he's about to kill.

Himekawa praises Oga and then asks if the latter would like to be his subordinate, even going as far as to try and bribe Oga. He claims that it will serve well in unifying the school. Oga bluntly refuses and, when one delinquent ridicules him for going against a Tōhōshinki member and the son of a conglomerate, kicks the underling and states that he doesn't even know Himekawa. Himekawa realizes Oga's strength and decides to challenge him on his own. Oga manages to land a punch on Himekawa, punching through the armor under Himekawa's shirt. Himekawa then uses an electric baton. Oga dismisses the shock as nothing compared to Beel's cry. The Zebul Spell on his hand begins to extend across his arm, in the process.

Hilda then frees herself from her bonds, having pretended to be caught by Himekawa's underlings, and Oga then starts charging some of Beel's electricity onto his marked arm. He punches Himekawa with the attack, causing the latter to cough up a lot of blood, and becomes victorious in the fight. It is then revealed that Hilda had allowed herself to be kidnapped, as it was the only way for her to test Oga. She and Alaindelon then leave the building, where it's revealed that Oga's attack destroyed a large portion of the warehouse. Hilda mentions how Himekawa, who was eventually sent to the same hospital as Kanzaki's, would've died if the building hadn't absorbed much of the attack.

Queen of the Tōhōshinki
Oga and Furuichi lounge on a bench in a local park, along with Beel who is drinking from a milk bottle. Oga starts discussing how impossible it must be for him to not fight and Furuichi begins to apologize, angering Oga as his Zebul Spell wouldn't have gotten so big if Furuichi hadn't gotten himself captured. The two have a brief argument and start talking about Hilda's actions, which have affected both males in negative ways. As they talk, Oga notices that Beel wants to be thrown up in the air to which Oga decides to do. However, he notices that he threw Be'el too hard and starts running after the Demon Lord, not wanting to suffer a fatal electrocution.

On the other side of the park, a group of mothers start gossiping about Oga raising Be'el until one of them notices a girl with a little boy, named. They then start gossiping about the girl, talking aloud about how she's raising a child despite being 17 years old. The girl is annoyed by this, especially because the boy on her back is actually her younger brother. She tries to explain things to the mothers but notices Beel flying towards them instead. Oga suddenly rushes past her and narrowly catches Beel from falling. The mothers recognize him as the delinquent they were talking about earlier and start insulting him, calling him a "child-abuser". Oga suddenly realizes that he's in the middle of his "park debut", a "park debut" being a public step-up when raising a child. Oga attempts to change the mothers' impressions on him but he unintentionally frightens them, causing them to run away. Oga then notices Aoi, who was laughing at how he frightened the mothers, and unexpectedly asks her to go out with him. Aoi is surprised by his question, skeptical even, but then Oga tells her that it's for the "park debut". Although annoyed by how vaguely he asked her about it, she agrees to help him. She quickly explains how she's not a mother and how the boy with her, whose name is Kōta, is actually her younger brother. Aoi notes how Oga doesn't appear to be a bad person, though she remains skeptical. Shortly thereafter, the same group of mothers who left have returned along with a police officer, who was informed that Oga is a child-abuser. The police officer notices Aoi and tries arresting Oga so that he can impress her, though Aoi tries defending Oga when he does so. The officer then starts insulting her along with Oga, stating further that the future will be grim with teenagers becoming parents. Aoi is angered and attempts to slap him but Oga, also feeling insulted, punches the officer and disposes of him in a nearby trashcan. Oga notices the expression on the mothers' faces and quickly leaves, as his "park debut" has been apparently ruined. Aoi and Kōta then return home though Aoi notes how she never got a chance to learn Oga's name. At home, she is greeted by the Red Tail members before changing from her disguise. She is revealed to be Aoi Kunieda, the sole female of the Tōhōshinki.

A week later, Oga awakens and notices that his Zebul Spell has reduced to its original state and cheers out loud. Hilda is surprised by this, then angered when she learns that it's (probably) because Oga only played video games the whole week. Afterwards, she has Oga help her construct a toy that she received from the Demon World for Beel. However, they are eventually trapped inside due to the toy's gameplay. They read the instructions and learn that for them to be freed, another player has to complete a kiddish shape-sorter game. Beel awakens and plays with the shape-sorter after Hilda and Oga pointed it to him, though he is incapable of playing it properly and eventually breaks it. Angered, Oga breaks free from the cage that sealed him and Hilda, much to the latter's surprise. The Zebul Spell returns to its former, extended state much to Oga's disdain.

At the local hospital, it's revealed that Kanzaki and Himekawa were placed in the same hospital room where the two start arguing about simple disagreements. They are soon visited by Shiroyama and Natsume, who inform them of Aoi's return to Ishiyama High after conquering northern Kantō.

Oga and Furuichi are also informed of Aoi's return and, upon discovering that girls also occupy the school, Furuichi decides to go meet the "queen" of Ishiyama High School. Oga, still wanting to get rid of Beel, also goes. Kunieda and some of her female delinquents, members of the Red Tail, are also searching for Oga after learning of what he did to Kanzaki and Himekawa. When they meet, however, Aoi recognizes Oga from the park but not vice-versa. Though she still regards him as a good person, due to her leadership of the Red Tail, Aoi still decides to fight him. When Oga refuses to move Beel away from them, she rethinks her opinions and slashes at him. Oga dodges her attack, surprising her, but she then uses Nishiki Hyakka Midare Zakura against him, which he also dodges. Oga notices that Beel likes Aoi and suddenly asks her to become his mother, though she misinterprets his words and starts to fluster. When Aoi hears him say, "Ah oh!", which sounds a lot like her first name, she then leaves in embarrassment.

In one of the classrooms, Red Tail members Nene Ōmori and Chiaki Tanimura discuss how Oga tried to trick them. Aoi ignores them and instead wonders aloud whether Oga is divorced, much to Nene's and Chiaki's horror. While alone, the two talk about Oga in the hallways and how Aoi is apparently in love with him. Meanwhile, Oga is with Furuichi and they talk about Aoi. Oga mentions how he wants to give Beel to her and Hilda, who arrived to drop off Beel's milk, overhears him. She states that she'd like to meet Aoi, especially after hearing how Beel has actually taken a liking to the female delinquent.

Suddenly, they are confronted by another delinquent group of Ishiyama High: the MK5. Ikari of the MK5 then starts taunting Oga, Hilda, and even Beel. Angered by this, Hilda attacks him and the other MK5 members with her parasol. Oga then joins his "wife" in this rampage. The two then defeat MK5. Afterwards, Beel notices an evil-like presence and looks around, spotting the last member of the Tōhōshinki, Tōjō.

Nene and Chiaki, after their own private talk, have an intervention with Aoi. They ask about her feelings for Oga, for which Aoi denies. Nene then remind her that as a Red Tail member, she cannot have intimate relationships with men. Aoi knows this rule and tells Nene that she understands though when she hears about Oga fighting the MK5, she rushes off to find the male delinquent. Arriving at the scene, she sees Hilda and learns that she is Oga's "bride". Aoi is angered by this and storms off, vowing to kill Oga. Oga and Furuichi have already left the vicinity but without Hilda. Furuichi asks how Oga plans to give Baby Beel to Aoi, also noting on how Aoi isn't really an evil person. Oga realizes Furuichi's points. Natsume then approaches them from the school, talking through an open window. He notes on how Aoi is a strong woman and that now, Oga only needs to fight Tōjō. Soon afterwards, Nene and Chiaki confront Oga and ask to speak with him and in the meantime, Hilda also confronts Aoi. Hilda and Aoi start fighting each other. Aoi proves herself to be capable of withstanding many of Hilda's Demonic attacks. At the end of the battle, Hilda notes how Aoi isn't as strong as Oga although she admits that the Red Tail leader is an impressive warrior. The two are then approached by more members of the Red Tail, who inform Aoi that Nene and Chiaki were defeated by Oga. Angered, Aoi confronts Oga again on the school rooftop. She tells him that since he's after her, he should have just came to her first. Oga thinks this is about him trying to pass Baby Beel onto her. Aoi then asks what Oga did to "those two", causing Oga to mistakenly believe that she's referring to Kanzaki and Himekawa. He states that he just beats down weak people as soon as possible, unintentionally angering Aoi even further, causing their fight to become even more serious.

In a flashback from when Nene and Chiaki approached Oga, it was shown that Oga never beat them up as he was too busy running after Beel after the infant had (comically) fought a stray cat. As Nene and Chiaki were leaving, they were attacked by an unknown assailant.

Nene then wakes up in the school's nurse's office and, after learning that Aoi and Oga were fighting each other again, rushes to the rooftop to find her leader. As she climbs the stairs, she finds other Red Tail members beaten by the MK5, angering her. Also on the rooftop are Ikari and a delinquent named Miwa, both of whom plan to defeat Oga and Aoi after the two are weakened from their own fight. It turns out that while Ikari just wants to control Ishiyama High, Miwa only wants Aoi gone just because she holds the title of "Queen". The fight between Oga and Aoi intensifies and she then uses Ichishiki Hagan Kiku Ichimonji. The other members of MK5 notice her attack and Chatō points a handgun at Nene's head. Thankfully, Natsume appears (as he heard why Aoi plans on killing Oga, and why she shouldn't) and saves Nene from MK5. Nene rushes to the rooftop, where Oga is unconscious on the ground, and tries to tell Aoi about Miwa's plan but is interrupted by the said person. Miwa asks Ikari to dispose of Oga, but Oga awakens and punches Ikari for interrupting his fight. He defeats Miwa, as well. After which, he asks to resume his fight but Aoi admits defeat. Before she can fully explain herself, Oga tries passing Beel on to her again (still unaware of why she was fighting him in the first place). Meanwhile, Furuichi watches from afar, feeling envious of Oga and what other (seemingly good) things may happen to him. Hilda, who was also watching, calls Oga 'trash' for refusing to lay hand on Aoi, a woman. Oga is then asked why he's trying to pass off Beel to other people and tries explaining his situation, as well as how Hilda is involved in it, but he ends up making Aoi and Nene believe that "Hilda is an evil woman who forces people to raise her children for her". Hilda then approaches Oga and tells him that they have to leave, as Aoi cannot raise Be'el. Aoi then asks if Hilda feels any guilt for forcing her children on others, but Hilda simply replies that they can fight anytime as long as Aoi gets stronger. This causes a rivalry between the two, as well as the end of Aoi's reign as "Queen" and leader of the Red Tail.

Fighting to be the Father
It's now summer break and Furuichi, who was off at a beach resort, is taken to Oga's room by Alaindelon. There, the two teenagers go to the public pool. At the pool, Furuichi meets Nene and Chiaki and they talk about Oga, as well as Aoi. As they talk, delinquents from Furuichi's old middle school arrive. There is a brief argument between the males and after one starts taunting Furuichi, mainly how weak he is, Furuichi headbutts him and flees to hide underwater in the pool. He is eventually uncovered and soon, he notices Oga and Beel still in the pool while on a floater. As the delinquents enter the pool, Furuichi pulls Oga and Be'el underwater as he hops atop the floater. Beel cries and electrocutes the water in the pool, save for Furuichi.

Later during the summer, Alaindelon becomes a resident of Furuichi's home while using the same pitiful act that Hilda uses on the Oga family, but Alaindelon only makes things very uncomfortable in the household. Around the same time, the weather becomes extremely hot and Beel suffers a fever. His body temperature has risen to the level where he can even melt a Popsicle without touching it. Beel's fever doesn't get any better even when the weather is at a more normal temperature. Hilda becomes worried and starts tending to Beel and while she does, she notices that Oga's Zebul Spell has disappeared. She becomes upset and literally kicks Oga out of the house, stating that she's disappointed in him. Oga walks around town during the night and is confronted by Shōji Aizawa, an underling of Tōjō's. They briefly fight each other and Oga then returns home, finding Hilda to be gone. The next day, Be'el has disappeared as well and his older sister Misaki forces him to find his "wife" and "son". Oga, along with Furuichi, then go to the nearby river and find Aizawa there. Aizawa then introduces Hidetora Tōjō to the two, the Tōhōshinki member having Baby Beel atop his back.

Oga, realizing that Beel is now with Tōjō, starts cheering but in a nervous, almost agitated manner. He tries to leave by crossing the river but Furuichi stops him, reminding him about how Beel is mysteriously with Tōjō. Oga then asks Tōjō about this but the Tōhōshinki member says that he'll only tell if Oga beats him in a fight. The two fight by throwing punches at one another. The first time, Tōjō sends Oga into the river while the second time, Tōjō is thrown far back onto the grass. They then continue their match and it ends with a bloody headbutt, to which Tōjō thanks Oga and proceeds to explain about him and Be'el. But Oga continues to fight, as Tōjō doesn't actually have reason to tell him anything. Tōjō then sends a massive punch to Oga, throwing the latter far across the river, and then leaves along with Be'el and Aizawa. In a flashback, it's shown that Tōjō actually found Baby Beel after finding him near a dumpster. He decided to keep the Demon Lord after Beel became attached to him, the infant noting on how similar he is to Oga.

Oga returns home where Hilda invites him back in. She states that because Beel's fever isn't getting better, she requested that specialists come and help from the Demon World. The specialists are the doctor Furcas Rachmaninoff and his assistant Lamia. Furcas notices that Beel is nowhere to be found but has already come to a conclusion on what is happening to Beel, based on already-given information. Beel apparently has "King Fever", a disease that affects members of the Royal Family with exceptionally large amounts of Demonic power. He states that since Beel is in the Human World, where he needs a Human contractor, Beel unintentionally cut off his contracting link with Oga because the latter couldn't process Beel's power completely. Hilda offers to help Oga synchronize himself with Beel again. Oga denies it and states that he only wants to fight Tōjō, but Lamia pulls out her pistol and says that he's too loud. The pistol is supposed to help with the synchronizing process. She shoots it at Oga, knocking him out. It is then revealed that Oga is sent into a loopy dream, where waking up is only possible if he's reconnected with Beel. In his dream, Oga experiences many strange phenomena (such as an extremely muscular Furuichi, for example) until he finds Baby Beel. There, he begins the process of synchronizing the two. The three Demons watch as Oga is writhing in pain, wondering what's about to happen to him. The process took almost 6 hours to complete. Oga, upon waking up, spanks Lamia for shooting him in the head. He then takes a shower but is interrupted by Shiroyama. Oga initially believes him to be Lamia in disguise but Shiroyama corrects him and then takes Oga to a park where Kanzaki and Himekawa are at. The two then explain the situation to Oga.

Earlier that night in the same park, Tōjō was with Aizawa and another underling, Kaoru Jinno. They talk about Oga and also Beel but as they discuss, Kanzaki and Himekawa appear having been checked out of the hospital. The other two Tōhōshinki members agree to help fight against Oga but also claim that Tōjō stole their underlings from them. Kaoru states that their power levels have decreased dramatically, and thus Tōjō's is higher, but adds that they had nothing to do with Kanzaki's and Himewkawa's underlings leaving them. Tōjō mentions that they can fight if the problem remains, to which Kanzaki tries to do, but the two are then easily defeated by Kaoru instead.

Kanzaki and Himekawa still want to kill Oga for what he did to them, but now they want to kill Tōjō first. Oga initially disagrees, stating he wants to do everything alone, but ends up joining the two anyway. They walk to Ishiyama High School while it's still night but are approached by Aizawa. Later, more of Tōjō's underlings join them and eventually the four delinquents are surrounded. Aizawa then leaves, as there are more people who can dispose of the four. Himekawa and Kanzaki dispose of some delinquents while Oga finishes off the rest. They then continue on to Ishiyama High. There, they are surrounded again by even more delinquents. They state that this is war in their school and in order to keep things at bay, they must kill Oga and the others. However, suddenly Aoi appears along with the Red Tail, Aoi stating that they'll defeat the delinquents for Oga and the others. Aizawa appears before Tōjō who is shown setting up a bunch of fireworks which he stole from work, wanting to create some fireworks to make Beel feel better. Aizawa is clearly shocked by this. Kaoru then arrives and wonders why so many people are joining Tōjō, to which the delinquent then replies that he allowed them all to be. Tōjō then lights a match and uses it on the fireworks, causing a large firework in the sky. After that, Oga then appears to fight Tōjō. At the same time, Furuichi is woken from his sleep by Alaindelon who then sends him to Ishiyama High where the battles are taking place. He witness Oga and Tōjō standing before their fight. He is greeted by Hilda and introduced to Furcas Rachmaninoff and Lamia. They then watch as Oga's and Tōjō's battle starts to commence.

Kaoru and Aizawa start walking around the school and are then confronted by Himekawa and Kanzaki, along with an accompanying Shiroyama. The two Tōhōshinki members want to fight and get their revenge on Kaoru, who tells them that they cannot defeat him. Still, the two are determined and their fight comes to a start.

Tōjō talks to Oga and tells him that he knows now that Beel is his son. He offers to hand Beel back to Oga, stating that he only wants to fight him. Tōjō then asks if Oga can fight better if he's fighting for Beel. Oga denies it all, stating that he's only fighting for himself and that Beel is not his son. Whether or not Beel wants Oga as his father is totally up to the Demon Lord. Hearing this, Beel's fever is immediately healed and he now draws the attention of Oga and Tōjō, as well as the others around him. Beel chooses Oga and crawls to his adoptive father, then climbing up to the top of his head and cheering about it. Tōjō is happy for Oga, as he now is the rightful father of Beel. Still, he wants their fight to begin. Oga agrees and their fight begins.

From the sidelines, Furuichi notes how Tōjō is actually a normal, good-hearted guy who just likes to fight. Also, Lamia finds the fireworks that Tōjō stole from his part-time job. She'd overheard what he said about them and how he wanted to make Beel better with them. As she thinks about it, she notices how one fuse hasn't been lit yet.

Aoi and the Red Tail then defeat the rest of the delinquents. Aoi is praised by a fellow Red Tail, Yuka Hanazawa, and the girls all decide to go and watch Oga's and Tōjō's battle. Himekawa and Aizawa are still being beaten by Kaoru, who taunts them by stating that there comes a time when leaders have to back down from power. Aizawa joins in and states that they should be thanking Oga for helping them back down, but the two Tōhōshinki members state that they can't keep anything without fighting for it. They add further that carrying a burden will only make them stronger and that it will profit off of others. Natsume then gives an applause for the two on their speech and helps defeat Kaoru. He also states that they should find Tōjō.

Tōjō and Oga start off by throwing punches at one another but Oga backhands one of his throws, catching Tōjō by surprise. He throws even more punches at him and even tries going for a kick to the face but Tōjō blocks with a headbutt. Tōjō gets excited and starts attacking Oga more viciously, even starting to gain an advantage on him. But Oga gets angry and tries to attack again. His attempt, however, activated his Zebul Spell attack. Lamia notices this and accidentally sends one of the fireworks rolling down to the two. But Oga touches the firework and, because he used the Zebul Spell technique, causes an explosion that results in a ring of fire stylized as the Crest of the Royal Family. Tōjō is impressed and wonders what Oga really is. However, Oga is angered and tells Beel not to interfere with their fight, stating he won't lose. Hilda notices this and realizes that the trust between the two is stronger than ever. The two then continue fighting each other until Oga deals the finishing blow on Tōjō: slamming him headfirst into the ground.

Tōjō is then defeated, much to the surprise of those around him (including the newly-arrived Red Tail and Aoi). Be'el hops back on Oga's back and the two are greeted by Furuichi, who then asks about the Zebul Spell on Tōjō's arm. Tōjō explains that he used to admire a certain man from his childhood who had the same tattoo as Oga's, and that the one Tōjō currently has is not an actual contracting seal. He also names Oga as "the best of Ishiyama. Furuichi then wonders how there are other Demon contractors like Oga.

Soon afterwards, Oga's contracting arm starts bloating rapidly, much to the confusion and shock of those around him. Hilda then immediately tells Oga that he will die if he doesn't hit something with the Zebul Spell, as it is currently overflowing with Demonic magic. Rushing to hit something, Oga punches the ground and accidentally destroys the entire school.

End of the Summer
Oga and Furuichi, both bandaged, are sitting on a bench along with Beel and discuss how Oga broke his vow, again. Furuichi is enraged at how Oga changed their Freshman year so easily ever since he contracted with Beel. Furuichi argues how they no longer have a school though Oga couldn't care less about what's to happen next, angering Furuichi even further.

At the local hospital, all the other delinquents of Ishiyama High (save for Tōjō and the female students) are there, with a vast majority of them being under emergent care. It's revealed that Oga's attack also injured the students, as well. Natsume talks about Oga and Tōjō to Kanzaki, Himekawa, Shiroyama, Aizawa, and Kaoru. He also states how Oga causes much of their injuries and the school's destruction.

Oga later takes Beel out to go train at Mapputatsu, as Beel continues crying after seeing a "half-dead cicada". Oga decides to train Beel by tying him from a branch and threatening him with a cicada, but the branch snaps and causes the two to fall. Upon falling, Oga meets Aoi (who's in her disguise) but recognizes Kōta. He also recognizes Aoi but not as Aoi Kunieda, stunning her. The two then get ice cream where he then asks Aoi's name. Aoi starts off by saying her last name but before she can finish, her grandfather appears and calls out her first name. Oga then believes her name is Aoi Kunie, failing to recognize her as Aoi Kunieda. Aoi's grandfather asks of Oga's relationship with Aoi and learns that Oga is out for special training, both questions being answered by Aoi herself. Aoi's grandfather, Ittōsai Kunieda, then offers to help train Oga.

Oga obliges and offers Beel, confusing Ittōsai. Instead, Oga and Ittōsai start fighting but Oga is quickly defeated. Ittōsai then notices that a parcel he was carrying has gone missing and starts chasing after an unknown person who was seen leaving the vicinity, suspecting him of being the thief. Instead, he (and Aoi, who ran after him) finds three delinquents who tell him that they don't know anything. Aoi then whispers to her grandfather and Ittōsai then walks off the cliff, revealing that the three delinquents actually have the parcel. They start running away but Oga, who follows Aoi and her grandfather, punches one of them for getting in his way. Ittōsai then disposes of the other two, revealing that he hadn't fallen and was only formulating a plan with Aoi.

Ittōsai leaves and tells Oga that he can train at his house anytime, as he recognizes Oga as Aoi's potential husband. Aoi leaves with her grandfather, embarrassed, and Oga returns home. Beel then defeats a cicada, albeit an already- dead one.

Anime and Manga Differences

 * The scene where Alaindelon is floating down the river was toned down in the anime. In the anime, his head is only visible and an arrow pierces his throat. In the manga, parts of his chest is revealed and the arrow pierces his left pectoral muscle instead. He is also bleeding from the said area and from his nose.
 * In the manga, Aoi was informed of Nene's and Chiaki's defeat by two unnamed Red Tail members, one of which would later tell Nene of Aoi's and Oga's fight. The two girls are replaced by Yuka Hanazawa and Ryōko Asuka, the former being the one would later tell Nene the latest news.
 * When Hilda first returns with the toys for Baby Beel, this ocurrs before Aoi's introduction in the anime.
 * When Ishiyama High is destroyed by Oga, the entire school is shown to be totally destroyed and in ruins in the manga. In the anime, it has been distorted instead. Though structurally intact, the school is still set for reconstruction.
 * Tōjō makes his appearance earlier in the anime, appearing as early as Episode 12.
 * In Episode 16 instead of just Tanimura and Ōmori appearing at the public pool, all the other Red Tail delinquents (except for Umemiya) are present, as well as Aoi.