The Problem Solver 68 is a club in the Gehenna Academy that do illegal businesses, and take on many contracts involving the black market, due to that, they are mostly running away from the Disciplinary Committee, a club that enforces school disciplinary rules. The Problem Solver 68 consists of four female students, Aru, who is the chairwoman, Kayoko, the chief, Mutsuki, the captain and a naughty problem maker, and Haruka, the youngest and newest club member.