Sotsugyou M: Male Graduation - Seitokai Naga no Kareinaru Inbou 1998

Sotsugyō M is an "otome game"; a romantic adventure game aimed at a female audience. It is based on the manga of the same title by Kei Arisugawa and Kyoko Nishiomi, which is itself a spinoff of the Graduation series set in a private all-boys high school. The player is cast as the younger sister of student council secretary Ryūnosuke Sugita; her brother has mysteriously disappeared, and after receiving a strange phone call, she goes to Seiryū High School to investigate, and meets an unlikely group of boys who help her out. In order to find her missing brother, the protagonist follows a clue left by him and teams up with a group of boys from a local boys high school.