One day the otherwise peaceful atmosphere at Ourin Gakuen abruptly changes. Kusunoki‑sensei, known as the subheroine, leads a coup d'état in which most of the students seize control of the school and the principal is beaten. Now it falls to Yuu Sakurano, Yuzuki Kaede, and Nagomi Fujikura to reclaim the school from her and restore its former tranquility. This marks the beginning of a full‑scale war the school has never witnessed before.