Kucabara, third son of the great demon king, is stripped of his powers and exiled to the human world, where he scrapes by working as a defense lawyer. To earn his way back home he must reclaim Dark Matter from the souls of the damned: if he can prove a soul sentenced to hell was actually innocent, the Dark Matter is his. Aided by the dragon demon Bichula and the exorcist Idamaria, he takes case after case while the demon world he was banished from slides into chaos.