In a world where Japan's security rests in the hands of super-powered samurai and their masters called generals, Muneakira Yagyuu, the official swordsmanship tutor to the family of the shogun, arrives at Buou Academy in order to serve as head of the school's dojo. However, while he hopes this will be a routine assignment at an all-girl's school, everything changes when a strange girl falls from the sky with a power of a Master Samurai and no memory...