Manga by author Tachibana Yuu

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 "Kmpfer", a female fighter. The Kmpfer are destined to fight with other Kmpfer. The story starts when he is attacked by an unknown girl who happens to also be a Kmpfer.

Narrates the story of Kyuuki, a strong, proud fox demon who recently woke up and needs a host and Kamishiro Shin, a normal would be high school student if it wouldn't for "his ability" and for the fact that he got a hold of the black Grimoire that controls Kyuuki's existence.Shin is bound to the book as long as he is alive, thus not only he can't sever his connection to Kyuuki; but those who want the book's power are bound to come after his hide regardless of time and place.