Sei Luminous Jogakuin

Kaihei is an ordinary high school student who unexpectedly inherits the chairman role at St. Luminous Mission High School, an all-girls institution, following his grandfather's death. As the sole male student and new leader, he oversees school regulations, events, and discipline. Upon his arrival, he learns that one of the students has disappeared. With the help of his closest friends, he decides to investigate the case discreetly, aiming to uncover the truth before graduation without involving the local authorities.