Within a country akin to a tower, rabbits live in towns on the upper floors 1 to 13, and the oppressed wolves live in the lower stratum. The lower the floor, the worse the living and the security gets. To move up ones requires a key as proof of passage, though moving down is unrestricted. In that kind of country, everyday a rabbit named Bell has the job of capturing wolves, and will savagely kill any of them that are invaders. Among all this, a wolf appears by her side…!?

(Source: MangaNi)