Peace has settled over the zodiac world now that the long cat-and-mouse feud is over, but that quiet doesn't last. A strange new zodiac girl named Na-tan turns up, leaving the 12 signs puzzled and delighting Nya-tan, who is cheered by the newcomer's pure, direct nature. Then Chu-tan arrives with a warning of coming disaster: a seal has been broken. The zodiac signs are left wondering who Na-tan really is, and what kind of deity has woken from beneath that seal. The result is a single-episode ONA mixing comedy, action and fantasy.