The plot revolves around Natsuru Senou, a normal high school boy with blue hair. One day he wakes up to find himself turned into a girl. A stuffed tiger “Harakiri Tora“ comes to life and tells him that he has been chosen as one of the “K?mpfer“, a female fighter. The K?mpfer are destined to fight with other K?mpfer. The story starts when he is attacked by an unknown girl who happens to also be a K?mpfer.