Miko Hakaba, Sako Boseki, and Koko Furuido are elementary school students in a class comprising those who can use special powers. Informed by their new teacher that he is looking for the strongest student to become "Banchou," willing members of the class pair off and begin fighting each other.

Quickly, the three girls are the only ones left standing. Just as they are about to determine the ultimate victor, a youkai attacks the school. As it turns out, this special class was created to exterminate youkai that threaten humanity, and the Banchou is the one who will lead the fight against these enemies.