The tutors his parents gave him because of his poor grades are the Shinjo sisters, who have always mistreated him. During a tutoring session, the girls use him as an outlet for their stress, and his body and mind deteriorate. Then one day, one encounter leads to another and Manato gets to know Otomo, the owner of the secret club "Gentildonna". Eventually, the device he'd borrowed got not only the heroines, but everyone involved in it as well.