Iruma Suzuki, a good-natured boy who can't refuse a favor, in a strange turn of events happens to become the grandson of Sullivan, one of the Great Demons of the Netherworld! Iruma is doted on by him, and begins attending the Demon School he's chairman of....
Iruma wants to live a peaceful school life while hiding the fact that he's a human, but for some reason he's always the center of attention. Elite demons pick fights with him, he befriends a rare-animal-type(?) demon girl, and the strict student council president has her eye on him!
One by one, Iruma overcomes the troubles that pop up with his natural kindness!