Yayoi, a spirited high school girl, has inherited spiritual powers from her mother, which she uses to protect people. During a battle with the devil Ura, Yayoi's power transforms the devil into a black kitten. Now, even though Ura does not conceal his desire to "eat" Yayoi's power whenever he gets the chance, they develop an interesting relationship: the two begin living together, and Yayoi takes her new feline "friend" along on her adventures.