The seemingly eternal cat-and-mouse battle has ended, and now everyone is living peacefully. One day, an Eto-musume (Zodiac girl) named Na-tan appears, to the puzzlement of the 12 signs, and to the unreserved delight of Nya-tan (whose spirits are always lifted by the pure, straightforward Na-tan). Meanwhile, Chu-tan also appears and warns of a looming disaster. The seal ... has been broken. Who is this mysterious Eto-musume Na-tan? What in the world is the deity that has awoken beneath the seal?