Touka Mimori and his classmates are summoned to a fantasy world by the goddess Vicius to put down the Demon Lord, and the one skill Mimori draws is graded E-rank status-effect magic, which the goddess reads as worthless. Branded a failure, he is dumped into the Ruins of Disposal, a dungeon no summoned hero has ever walked out of. Down there he finds that his abnormal-status abilities far outstrip their rank, and he starts working his way back up with a debt to collect.