The Netherworld. The world where all Demons live, and the monarch who rules is The Demon King! However, the Demon King's throne has sat empty for ages. Only the most worthy will inherit the seat of sovrienty. But who will it be?!

Iruma Suzuki, age: 14. One day, he found himself the grandson of a demon named Sullivan. Sullivan loves and spoils Iruma, and is even sending him to the most prestigous school in the land. But there's just one problem: The school Iruma's attending just so happens to be the demon school known as "Babylis." 

Dalet. The borderline rank assigned before graduation. To impose a requirement on Freshman students to achieve that rank is abnormal, indeed. Will Iruma and his friends manage to attain this goal, and avoid being thrown out of the Royal One? We'll have to tell you how that story turns out another time.