Discipline: Record of a Crusade

The story revolves around Takuro, a transfer student to a mostly female populated boarding school St. Arcadia. After being admitted because of his sexual prowess, Takuro moves into the same dorm as Saori, Yuuki, Luli, and Maiko, where Yuuki discovers that he has a special capability - an "Ultimate Sex Power". Having knowledge of Takuro's prowess, Leona wants him to be part of the Social Club, to which she is the leader of, with the intent of making him her own personal sex slave. (wikipedia.org)