Students at Ishiyama High School either dread Tatsumi Oga or aim to topple him, yet the young fighter is distracted by other duties—such as caring for baby Kaiser de Emperana "Beel" Beelzebub IV, the offspring of the Demon Lord.
Hildegard "Hilda," Beel"s caretaker, tells Oga that the babe has bonded with him because of his prodigious power. Consequently, Oga must shoulder the duty of raising the Demon Lord"s child or risk Hilda"s sword—unless he can enlist a stronger contender to persuade Beel. Maybe Oga could persuade one of the Tohoshinki, Ishiyama"s quartet of top fighters, to assume responsibility for Beel.