Saint Luminous Jogakuin

Kaihei is a rather normal high school student but soon discovers that his deceased grandfather has left him the chairman position of his all-girls high school, St. Luminous Mission High School. Besides being the only male student on campus, he is also now the young chairman in charge of campus rules, happenings and punishments. When Kaihei arrives however, it seems a student has gone missing. Kaihei, along with his closest friends, are now determined to solve this mystery (without getting the local police involved) before graduation.

(Source: Anime News Network)