For a long time, Aoi Nanamori was trapped in Himari Momochi's ancestorial house as its spiritual guardian, the Omamori-sama. Now, several years later, Aoi has returned to Himari as a human, and the couple is living together' although strangely the two are now further apart in age...

Aoi Nanamori is searching for proof of his existence by looking into the roots of his family name when the descendants of two other ancient families in the area, Mitsumori and Niimori, come to him with a problem: There is a monster in the Mitsumori house.