Gakuen☆Shinsengumi! Jikketsu Ibunroku  

A girls' boarding high school exists and has gained a reputation as a prestigious institution. However, enrollment numbers are declining. The vice-principal proposes that the school become coeducational, but the principal rejects the idea. As a result, students divide into two separate groups. Several days later, a boy is transferred to the school for testing purposes. This leads to a heated conflict among the students.