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 Be'el) 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 Be'el 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 Be'el'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. Be'el 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 Be'el's head and calms the latter down, then turning to walk around. A steel tower begins to fall over Be'el 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 Be'el are sitting in his room, the former stating that Be'el will become a great Human-destroying Demon Lord.

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.