Sotsugyou M: Male Graduation - Seitokai Naga no Kareinaru Inbou

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.

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.