Tatsumi Oga, a delinquent student at the worst high school in Japan, arrives at school with a small baby who emits massive shocks of electricity whenever it cries. Oga claims he found after splitting open a strange man who came floating along the river, though his friend Takayuki Furuichi doesn't quite believe. Whilst at Takayuki's house, they are both approached by a demon woman named Hildegarde who claims the baby, known as Kaiser de Emperana Beelzebub IV, is the son of Devil King who was sent to Earth to find a human to raise him so he could destroy humanity

Hildegarde presents herself to Oga's family in the wrong way, giving them a different view of the situation. She also informs Oga that if he is more than 15 meters away from Beelzebub, his cries may destroy the city. Whilst dealing with this situation, Oga comes up with the idea that, if he can find someone more strong and ruthless than him, he can dump Beelzebub on him and be free

When Oga loses some food for Beelzebub and he starts to get hungry, Oga instead uses up a vending machine's worth of yoghurt drink, revealed to be the favourite of the second year delinquent, Hajime Kanzaki. Figuring he may be worthy of dumping Beelzebub on, Oga goes to see him under the pretense of becoming his henchman. After beating his current henchman, Oga is asked by Hajime to throw him out of the window, but instead decides he isn't worthy based on Beelzebub's expression and knocks him out instead

Beelzebub is currently in a phase of non-stop urination that threatens to flood the city. Hildegarde manages to temporarily stop it with an interdimensional diaper, but in order to stop it completely, Oga decides he needs to get a super absorbent daiper advertised on telly. Upon reaching the supermarket only to find the brand had already sold out, it is taking hostage by a group of thugs

After a sleep deprived night, Oga notices he has a strange mark on his hand, revealed to be Zebel Spell, a symbol of the contract between him and Beelzebub. Hildegarde and Alaindelon explain that a Demon Lord's parent is a vessel for his power, and the mark will grow the more opponents Oga defeats. Wanting to get rid of the mark, Oga decides to give up fighting in the hopes it'll make the mark smaller

The mark on Oga's arm goes back to its small size, much to the chagrin of Hildegarde who destroys his games console. She brings a play room for Beelzebub to play in, but upon building it, it turns out to be a magical cage that both she and Oga get stuck inside. The only way to get out is to have Beelzebub solve a block puzzle toy, but he just ends up breaking it

Oga's family coerce him into taking Beelzebub to the park so he can make his 'park debut'. Despite making a bad impression with the other mothers, Oga meets a girl named Aoi who is looking after her little brother, Kouta. Aoi tries to help Oga make his park debut which, partly due to the appearance of Alaindelon, doesn't reap much success

Aoi and the Red Tails return to Ishiyama High to deal with Oga, despite not knowing who he is. When Takayuki drags Oga to meet her, Aoi is shocked to find Oga is the one she met at the park, although he doesn't recognize her back. Aoi starts to fight him using powerful bokuto attacks that cut through glass, but he manages to dodge all of her attacks

The delinquent group, MK-5, come to confront Oga, but are promptly beaten by him and Hildegarde, who catches the attention of a smitten Aoi. As Aoi's right hand ladies, Chiaki Tanimura and Nene Oomura confront Oga, Hildegarde, who had heard from Oga about his plans to dump Beelzebub onto Aoi, challenges her to a fight to test her strength. When Aoi returns to find Chiaki and Nene injured, she assumes Oga is responsible and confronts him in a fight

A stray cat becomes attached to Oga, causing Beelzebub to become extremely jealous and shock anyone he shows affection towards. Beelzebub challenges the cat to a fight and subsequently loses, but when a gang of fierce cats gang up on the cat for fighting in their territory, Beelzebub stands up for him, prompting Oga to help out. Afterward, Beelzebub and the cat become friends

Himekawa plots revenge against Oga by setting him up with a poisoned sandwich, but it doesn't affect him due to his resilience to Hilda's cooking. He next attempts to use a popular costumed character in order to try and capture Beelzebub, but Oga and Beelzebub notice that he's a fake due to differently colored chopsticks. He later attempts to seduce Takayuki into giving him Beelzebub, but Alaindelon intervenes, transporting Himekawa and his gang to a far off island

Beelzebub has been crying all night for the past three nights, which is causing Oga and the whole neighborhood to get very little sleep. Wanting to stop his night crying to avoid being chased out of their house, the Oga family attempt to play with Beelzebub all day in order to tire him out come nighttime. Despite managing to get him to sleep, Beelzebub still wakes up and cries in the middle of the night

As Ishiyama High holds an assessment test for its studyphobic students, the Great Demon Lord also holds a test for Beelzebub, requiring him to earn points by beating up various things, or run the risk of both he and Oga facing remedial classes in the Demon World. With Beelzebub not showing much hope, Oga decides to try and dump Beelzebub on whoever scores highest on the test. When a rival school interrupts the test, Oga fights them off to allow the other students to keep on the test, earning enough points to avoid remedial lessons, later learning that the smartest student it actually Takayuki

As Kanzaki tries to come up with a new special move to beat Oga, his followers suggest the key to Oga's power is having Beelzebub on his back. Thus, Kanzaki starts training with a weighted baby doll on his back. When that plan doesn't work, they try finding a living substitute, which end in more embarrassing results

Takayuki tells Oga about the final member of the Tōhōshinki, Hidetora Tōjō, mainly to get him interested about ditching Beelzebub so Alaidelon will leave him alone. Wanting Oga to get beaten, Himekawa informs them that Tōjō works at the beach. Oga and Tatsumi go there the next day and get mistaken as part-timers for a yakisoba stand, later finding that Tōjō had actually been fire the previous night

Takayuki is dragged away from his tropical summer vacation against his will to join Oga and Beelzebub to a public pool, though Oga is soon shocked by the fact he could've gone to the tropical resort himself. Whilst chatting with the Red Tails, Takayuki is approached by some delinquents from his old middle school and ends up going against their leader, Takashima, when they start hitting on the girls. Takayuki tries to hide in the pool, but Takashima calls more of his men and tricks the lifeguard into evacuating the pool, leaving Takayuki and a stunned Oga

The Demon King sends Beelzebub some summer homework, containing a notebook which brings anything drawn in it to life. Next, Hilda brings Oga to Ishiyama High to collect prints of rare, powerful beasts, aka the delinquents, by whacking them with a giant fly swatter. During the chase, Beelzebub ends up planting several carnivorous Demon Plants, one of which grows into a massive giant causing havoc until Oga destroys it

Beelzebub gets a summer cold, causing his body to give off incredible heat. As his condition gets worse, the Zebel Spell on Oga's hand disappears, leading Hilda to become frustrated towards Oga for showing little care towards him. As Oga tries to decide what to do, he encounters one of Tojo's henchmen, Shojo Aizawa, who seemingly outmatches Oga before leaving

Oga returns home after being defeated by Tojo to find that Hilda has returned from the Demon World with the imperial doctor, Forcas Rachmaninoff, and his assistant, Lamia, to help determine the cause of Beelzebub's illness. He diagnoses the illness as King Fever and when Beelzebub was trying to draw out massive amounts of demonic power, he accidentally severed the link between him and Oga and found Tojo similar to Oga and connects to him. Oga begins a treatment to try and reconnect with Beelzebub and enters a dream world through the effects of a Demon World drug that is shot into his head where he eventually finds a sleeping Beelzebub in the middle of several inscribed circles that are shrouded in an electrical field

Oga reflects on Lamia telling him to take a shower before going to Tojo and sees a silhouette outside his bathroom window and thinks it's Lamia, but it's really Shiroyama, who takes Oga to Kanzaki and Himekawa who tell him they want to team up to beat Tojo and Oga agrees. On the way to Ishiyama High, they are surrounded by a large group of delinquents, which Oga takes care of swiftly. Upon arriving at Ishiyama High, the rest of the school is there to confront Oga, only to have Kunieda and the Red Tails take care of them for him

Furuichi is woken up by Alaindelon at 4:00 A.M. and is teleported to Ishiyama High to watch Oga and Tojo's fight with Hilda, Lamia, and Forcas Rachmaninoff

Baby Beel's fear of insects prompts Oga to give him some special training up in the mountainous village of Mapputatsu. There, he stumbles across Kunieda carrying Kōta in the disguise she wore at the park with her grandfather. While Oga is still unaware of her true identity as Kunieda, her grandfather develops an interest in him

As the Zebub Spell is restored, Lamia and Dr. Forcas begins to return to the Demon World through Alaindelon. While they were being transported, Baby Beel grabbed onto Lamia and refused to let go, causing Furuichi and Oga to be transported as well

Finding Alaindelon's daughter rather attractive, Furuichi vows to rescue her while Gare and Edda leaded him to Oga and Lamia in the village of thieves where Alaindelon's daughter, Angelica is trapped. The rescue runs smoothly until a large Demon named Vlad's Master is awakened and terrorizes the village in which Beelzebub suddenly growed bigger and larger to fight it off

The students of Ishiyama High settle in at St. Ishiyama, with all the significant characters being placed in the same classroom. Their new homeroom teacher, Sadohara, challenges Tojo to an arm wrestle to try to establish some authority over the class, failing miserably when Tojo accidentally slams him upside-down against the wall

Oga and Furuichi accept Kazuya as their student, after being praised on how legendary they are. Kazuya tries to copy Oga to become strong like him, even making identical lunch boxes. Due to the Teimo incident, Oga and Kunieda meet Kido, the teacher in charge of student life at Saint Ishiyama Academy

In order to make up for forgetting his daughter's birthday, Alaindelon brought Angelica to Furuichi's house for a tour of the Human World. Unfortunately while the gifts were being retrieved from Alaindelon, a Yople alien teleported into the human world and escaped. Angelica resolves to track down the Yople, using a demon wand that transforms its user into a Magical Girl

The students of Ishiyama High are ordered to do physical examinations amongst themselves. Baby Beel gets jealous of a toy which accidentally gets stuck to Oga's back, and locks himself inside of a locker to pout in protest. While trying to lure him out, the girls come into the room for their physicals, forcing Oga and Furuichi to hide under the desk while the girls strip off and start measuring

After being shocked early in the morning by Baby Beel, Oga's enthusiasm to find someone new to pass Beel onto is temporarily reborn, and upon hearing rumors of six students who excel both academically and athletically, he goes off searching for these six in the hopes that they will impress Baby Beel. Oga, accompanied by Aoi, goes searching for Kazuya to get more information about the 6 Holy Knights. Meanwhile, Furuichi runs into an old friend, Miki

Furuichi and Oga survey the school from the roof searching for emblems on people's shirts, and Azusa ends up tagging along in their search. Two students from St. Ishiyama are seen hassling two of Aoi's gang, causing Shiroyama to interject, telling them to leave

The fight between Oga and Miki begins, with Miki seemingly beating Oga with ease. He strikes Oga with a technique which Aoi recognizes to be Hakkyokuken, a martial art form from China. Oga continues to fail to hurt Miki, using a variety of "special moves" which don't seem any different from his usual attacks

Hilda transfers into the class to keep an eye on how things are progressing, with Alaindelon transferring into another class. The students find out the sport will be volleyball, something none of them have any experience in. The students lack motivation which Hilda promises to sort out

Oga becomes tired of practicing and walks out of the gym, itching for a fight. He finds Miki training in a nearby Dojo, and challenges him to a fight. Oga takes all of Miki's attacks head on, and is clearly damaged from the strength of the attacks

The festival is underway, and Azusa is trying to run a Maid café. Furuicihi offers to help, and Azusa and her friends obey his commands blindly due to his reputation as 'The Strategist'. Furuichi persuades many of the Red Tails to dress up in Maid uniforms, claiming that this is a preliminary battle against a café that the 6 Holy Knights are running elsewhere

The match between Ishiyama and the 6 Holy Knights is here, and this is not your usual volleyball! With their pride and their educational future on the line, the Ishiyama gang puts it all out there on the court! Will Furuichi the Strategist be their trump card?

Kiriya, the man who scarred Miki and tried to attack Oga in the past shows up at the volleyball match. He declares that he is seeking revenge on Oga, and has taken hostages at the school to stop anyone interfering. Kiriya reveals that he had to move away to Nara previously, and this is why he is only now seeking revenge on Oga

Baby Be'el is having a great time at a railroad crossing and wishes Oga to sing with him. Oga, however, is thinking about the Izuma's words about demon powers. Aoi, who is happens to be behind them, runs into Nene and Yuka, and they once again assume Aoi is going to confess to Oga

Oga attempts to explain the whole situation to Aoi, but him and Furuichi get stuck on remember BabyBeel's name. Not long after, a demon maid servent who looks similar to Hilda named Yolda appears, and expresses her unhappiness on the situation. Soon another 2 demon maid servents appear along with a young boy who is introduced by the maids as Lord En, BabyBeel's older brother, who has come due to BabyBeel taking too long to destroy humanity

Before destroying humanity, Lord En wants to experience everything in the human world. As Lord En is a huge fan of games and the like, he is drawn to the game centres and amusement parks there and is distracted from his original mission of destroying humanity. During the visit to Ishiyama Land it's found that he cries very easily over the slightest things that BabyBeel does or happens in general

It's revealed that Tojo and Suzuka know each other from the past, as they both underwent training from Saotome. Izumo and Tojo have a fight after school and Izumo reveals some of his demon powers. However Behemoth's 34 Pillar Divison has arrived and causes trouble

Whilst everything is in commotion, Lord En continues his tour of the human world and is now in Akihabara. As usual, he also cries due the maids being mistaken for cosplayers and he feels left out. Also, Furuichi is called a pervert by Alaindelon's daughter

Hilda recovers and apologizes for everything and being unable to help. Oga decides to become stronger in order to protect everyone and so seeks for Aoi's grandfather to train him. Oga's younger sister is revealed to be a member of the Red Tails

Lamia asks Fruichi to find Baby Beel's brother but when they went to the game center, they find Kanzaki,Himekawa, and Yuko. Furuichi asks them for help. Meanwhile Aoi and Oga went for training to be strong

Oga begins his training with Ittousai while Furuichi and Lamia enlists the help of their Ishiyama classmates to search for Lord En. Can Oga and Beel complete their training in time and will Furuichi and Lamia find Lord En before he destroys the city with his army?

Furuichi's group go to Himekawa's home, to start searching for En in online games. When they arrive they find the place is a giant skyscraper building, with several rooms dedicated to gaming. Most of the group have never played games, except for Chiaki, who immediately proceeds to find En in an online fighting game

The episode opens with a distinct sci-fi feel, before moving into the game, where the Ishiyama group are in the middle of getting their asses handed to them. They are unable to do anything against the tank. Then Yuka shows up, driving a giant robot called the Crazy Frog

The show opens seeing the 2 pillars who got beaten in jail, and 2 other pillars talking to them. One is Lamia's mom. They then cut to the main gang who are tired from playing video games

After Oga came back from his training he introduce his new technique called the "Zebul Emblem" and "Super Milk Time" (He learn it while he was training with Saotome and Black Baby Beel and Baby Beel is fighting over the milk and Oga Decide to drink it himself so Black Baby-Beel And Baby-Beel doesn't have anything to fight on) to remove the divider between Oga and Baby-Beel. Oga suddenly became powerful after drinking the milk and the demon power from Baby-Beel increase and Oga defeat the two Pillar heads and after that he became unconscious and the Pillar Head Naga also fight Oga and Oga drink more of the milk then He and Baby-Beel merge and they became more powerful Oga Grew a wing and Scattered the Zebul Emblem to surround the Pillar Heads and at last he defeated the three Pillar Heads and the top of Himekawa's hotel was destroyed due to the explosion

A tired and thirsty Furuichi finds himself in a desert, accompanied by Oga, Baby Beel and Kunieda. Furuichi asks what the hell is happening but Oga replies that this is Journey to the West, that he is the monk Sanzohoshi and they are traveling to Tenjiku (India) to retrieve the Buddhist Scrolls. Before dusk, Oga and company arrive at a village populated by people who look like Shiroyama

Due to the after effects of Super Milk Time, Baby Beel and Oga have swapped bodies. In order to return things back to normal, they try to look for Saotome-Sensei to see if he knows how to, however they are continuously disrupted by everyone else from the academy trying to start a fight with Oga (who is currently Baby Beel). Eventually, Baby Beel runs away after being drawn to a smell, and Hilda, Furuichi and Oga try to catch him, where they find him attached to Aoi

Oga is trying to think of a way to perfect Super Milk Time before they're attacked again whilst Nene and the rest of the Red Tails are trying to get Aoi back into the group by holding a fake meeting at Aoi's place and so persuading her. Aoi's demon magic is revealed to be thanks to Koma, a perverted demon whom she acquired at Mapputatsu Temple. Oga has found a new milk bottle which will hopefully help Super Milk Time and is asking Furuichi to try it, who is obviously reluctant as he is "busy"

It's the coldest day of Winter and St.Ishiyama is closed, however everyone from Ishiyama has still come to school as they were not informed of this until Kazuya and Azusa come in to tell them. Unable to go home due to the storm, everyone remains in school, until suddenly the delinquents slowly get beaten up - Kazuya then informs the others that the incidents are exactly the same as that in the counting song "100 Delinquents"

Oga ,Furuichi and their teacher (which was the Spellmaster) was searching for the black version of Baby Beel. Oga thought that it was so bored that it ran away. But actually it was because of Himekawa

When Black Beel has gone missing, Zenjuro urges Oga, Furuichi, and Beel to look for him before something bad happens. Meanwhile, Himekawa who has kidnapped Black Beel for his close resemblance to a lucky statue experiences great luck and wealth. Somehow, Black Beel has grown gigantic

Himekawa introduces himself and tells everyone how he makes his "super cool" pompadour: by hardening it with a hair gel called Pomade. Furuichi ignores him and mentions a man showing up. Himekawa thinks he's referring to the Legendary Warrior, Super Pompadour

Hilda notes that Oga and his friends are acting funny and that they're scheming something bad. Oga and Beel deny this, but do so in such a poor manner that Hilda easily notices they're lying. After Oga introduces the next episode, Hilda begins to think of a new dance for Baby Beel in place of the Pudding Pudding dance

Koma gets an idea from Oga's Super Milk Time training to switch bodies with Aoi Kunieda by offering her Manju. He has some fun moments with Aoi that gets pervy but he also spends a good bit of time with the kids, of which Koma fits in pretty well. His attempts to push them into his own designs are definitely fun since he wants to utilize the body switching ability for his own ends, which is essentially to get into Aoi’s body and play with her end

Behemoth visits St. Ishiyama to find Oga and Beelzebub, but he gets welcomed by Zenjuro, Ittousai, and the principal. Hilda holds Oga down while they watch the fight

While Aoi fights Agiel, Oga and Hilda meet Behemoth and Jabberwock up close and personal. Then, at Akumano Academy, Lord En and quetzalcoatl has the delinquents playing a "game," and at the same time, Oga fights Jabberwock to free Hilda from the enormous jaws of Sodom. Will Oga and Beel have the power to free Hilda from Jabberwock and his dragon, Sodom?

It begins with a bunch of Ishiyama delinquents crying and mourning over the loss of Oga and Baby Beel. Their tears stop short by the river when Alaindelon cruises like a speedboat and Oga and Beel pop out of the man. At Oga's house, Hilda explains that the Great Demon Lord has no interest in destroying humanity which means the goal of raising Beel to destroy all humanity is no more