She is a teacher at the all-girl high school.

One day the else so peaceful mood in the Ourin Gakuen suddenly changes. Kusunoki-sensei, the so-called subheroine, along with most of the students takes over the school after a coup d'&eacute;tat. The principal is beaten and now it`s up to Yuu Sakurano, Yuzuki Kaede and Nagomi Fujikura to take back the school from her and return it to the former peaceful days. <br><br>
This is the start of a full-scale war, one that this school has never seen before.
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(Source: Anime News Network)

Ryuuougi Kusunoki