For many generations, members of the Mizuchi bloodline have been pursued by Yokai, or supernatural creatures. Toru and Noboru Takagami are descendants of this lineage, and under the watchful eye of their grandmothers, they receive a clandestine weapon to combat these monsters. This armament is Tenko Kugen, a fox spirit who can transform into either male or female at will. Along with Ko, a shrine maiden, the Takagami brothers and Ko will now reside together in their household. Life has become more complex as a result of this revelation.