An introverted high school student, Souichi Sakuraba, is being bullied severely by the "Yokai" classmates. The bullying escalates, and Souichi's childhood friend, Azusa, who was the only one who trusted him, is defiled by them. In front of Souichi, who was in the depths of despair, the succubus, Asmode, appeared. Souichi makes a contract with a succubus who possesses a mysterious ability, and decides to make the bully's loved ones suffer the same pain as himself by "cuckolding" them.