->''"[[UnreliableNarrator Long long ago, in a certain place,]] [[BlatantLies there was a very handsome, cool, well-respected, entirely angelic young man...]]"''
This is the story of up-and-coming [[JapaneseDelinquents delinquent]] Tatsumi Oga, a first year at the infamous Ishiyama High, who one day suddenly finds himself [[ActionHeroBabysitter unintentional foster parent]] of the Demon King's son, Kaiser de Emperana Beelzebub IV (Baby Beel for short), an [[KillerRabbit adorable baby boy]] who is destined to [[EndOfTheWorldAsWeKnowIt destroy the world]]. Initially [[RefusalOfTheCall reluctant]] to carry out his fatherly duties, Oga changes his mind when Baby Beel's [[NinjaMaid wetnurse]] and "mother" Hildegarde shows up, with the news that Oga [[JoinOrDie will be killed]] if the contract is broken, and he must face his responsibilities. That is, unless he can find [[AsskickingEqualsAuthority someone even stronger]] to take over from him...
A [[CrazyAwesome delightfully absurd]] gag manga with liberal doses of action by Ryuhei Tamura, ''Beelzebub'' started out as a one-shot before being serialized in ''Magazine/ShonenJump''. The plot consists mainly of [[IdiotHero Oga]] dealing with the problems of raising Baby Beel, while fighting his way through the ranks of demons and troublemakers he encounters, often to [[HilarityEnsues 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.