Iruma Suzuki, a 14-year-old human boy, is sold to a demon named Sullivan by his parents. Sullivan adopts Iruma as his grandson and enrolls him in the Babyls School for Demons, a school for demon students, where he lives with Sullivan. Iruma quickly befriends Alice Asmodeus and Clara Valac, but he must keep his true identity as a human a secret to avoid being eaten by other demons.