In the serene atmosphere of Ourin Gakuen, a sudden upheaval occurs when Kusunoki-sensei, known as the subheroine, leads a rebellion with the students and seizes control of the school. With the principal defeated, Yuu Sakurano, Yuzuki Kaede, and Nagomi Fujikura must rally to reclaim the school and restore its former tranquility. Thus begins a fierce battle unlike any other the school has witnessed.