It was first published in 2008 as a one-shot in Shueisha's Weekly Shōnen Jump, subsequently winning the fourth Gold Future Cup.

The story follows Tatsumi Oga, who is a first year student at a school for juvenile delinquents called Ishiyama High.

Oga pulled him to shore but the man split in half, revealing a baby boy inside.

In the early chapters, he attempts to 'pass on' Beel to other students at Ishiyama, thinking that if he can find someone stronger and more evil than himself, the baby will attach himself to that person instead.

Oga attempts to prevent the seal from growing by avoiding fights with other students, but gives up when Himekawa, the second member of the Touhoushinki, captures Hilda and Furuichi.

Oga then infiltrates Himekawa's base to rescue them and defeats him by using the Zebul blast for the first time.

Hilda comments after looking at the crest that the amount of energy it used would have driven a normal human mad.

While visiting the park, Oga then meets a girl named Aoi and her brother, Kouta.

Aoi sees Oga and Hilda's fight with the MK5, and believes the rumors that they are husband and wife.

At the same time, Nene wakes up in the infirmary and goes to warn Aoi of MK5's trap, which turns out to be Miwa's scheme.

Once Oga gets home, he is in a surprise to find Hilda there waiting for him, with a strange demon doctor known as Dr. Furucas, and his assistant, Lamia.

Furucas reveals that the cold is actually Beel's way of coping with a rise of his power, by keeping the energy within himself, and that he cut off the link between him and Oga to protect him.

Initially, they are constantly looked down on, but after a volleyball match against the Six Knights, the negative views towards them stop.

During the volleyball match, Oga's demonic power is displayed due to a fight with someone who had a grudge on him, though it is covered up by the Saint Ishiyama president who claimed that it is just a trick.

A new teacher soon arrives to replace the one teaching the Ishiyama group, knocking out both Oga and Tojo on the same day before carrying them to the classroom.

The teacher, Zenjiro Saotome, later appears when Oga, Hilda and Aoi are attacked by Hecadoth, and puts up a fight against the demon.

Written and illustrated by Ryuhei Tamura, Beelzebub was first published as one-shot pilot chapter in Shueisha's shōnen manga magazine Weekly Shōnen Jump on August 11, 2008,[2] subsequently winning the fourth Gold Future Cup.

[10][11] The series' cast included Katsuyuki Konishi as Oga, Miyuki Sawashiro, Shizuka Itou, Aki Toyosaki, Tomokazu Seki, and Takahiro Mizushima.

[16] Oga appears as a playable character, assisted by Baby Beel, in the Jump crossover fighting game J-Stars Victory VS. Aoi, Hilda, and Alaindelon appear in the game's story mode as non-playable characters.