The king of demons sends his son, Prince Beelzebub, to Earth. However, this prince, who will destroy the world and disrupt the balance, is still a baby. Meanwhile, Tatsumi Oga, a delinquent in high school, unexpectedly finds himself as the caretaker of this baby named Beelzebub due to circumstances. Hilda, Beelzebub's actual caretaker, explains the situation to Tatsumi, but she cannot separate Beelzebub, who is tied to pure evil and very powerful beings, from Tatsumi. Tatsumi must take care of Beelzebub, who will bring about the end of the world; what will he do with this little one he can't be apart from for even a minute?
