明道高校の生徒、須藤優真は、廊下や教室を徘徊すると噂される「エロ怪人」を引き寄せないように、入学当初から同級生の女子生徒に対するエロティックな感情を抑え続けていた。Since day one, Myodo High School student Sudo Yuma has been repressing his erotic feelings towards his fellow female schoolmates in order not to attract the so-called “Ero Phantom” rumored to stalk the corridors and classrooms. Then one day, a new transfer student arrives and gets placed in his care.