Suzuki Iruma, a good-natured boy who can't refuse requests from others, unexpectedly becomes the grandson of the great demon Sullivan! Doted on, Iruma begins attending the demon school where Sullivan is the chairman... Although confused, Iruma still lives a happy school life with his classmates such as Asmodeus and Clara. He thought he had gotten used to the demon world, but one day, further suffering befell him! The ring began to speak, and Iruma... became a bad boy! ? Iruma's turbulent life in the demon school will continue!