Ruri is a clumsy kunoichi who fails at everything she does. The reason she never gives up and continues to work hard at her missions is for the sake of her sick sister, Murasaki.One day, Ruri learns that there is a bounty of 100,000 ryo on the head of Tokuyama Tenryo, the Shogun of the Edo Shogunate.Ed Castle, where Tenryo lives, is an impregnable, twisted castle. The clumsy kunoichi's quest to conquer the castle begins!