This is the story of up-and-coming delinquent Tatsumi Oga, a first year at the infamous Ishiyama High, who one day suddenly finds himself unintentional foster parent of the Demon King's son, Kaiser de Emperana Beelzebub IV (Baby Beel for short), an adorable baby boy who is destined to destroy the world. Initially reluctant to carry out his fatherly duties, Oga changes his mind when Baby Beel's wetnurse and "mother" Hildegarde shows up, with the news that Oga will be killed if the contract is broken, and he must face his responsibilities. That is, unless he can find someone even stronger to take over from him...
A delightfully absurd gag manga with liberal doses of action by Ryuhei Tamura, Beelzebub started out as a one-shot before being serialized in Shonen Jump. The plot consists mainly of Oga dealing with the problems of raising Baby Beel, while fighting his way through the ranks of demons and troublemakers he encounters, often to hilarious results.
An OVA was shown at the 2010 Jump Super Anime Tour. The anime adaptation began airing January 2011, ending in March 2012.
The manga ended in 2014 after 240 chapters, and the spin-off, named Beelzebub Side Story, concluded in March 2015 after six issues.