The year is 1590, during the turbulent Sengoku era of Japan. A girl who calls herself Izumi, the sole survivor of the destruction of her village, has come into possession of a set of very powerful keys. These keys can give their wielder access to powerful weapons that could change the course of the era.<br /><br />In her flight from those who want to kill her and take them, she has washed up in a buddhist monastery, where she has met the monk Tenkai. Tenkai, who takes an interest in her troubles, may be more than he appears!