Musashi Sasaki returns to his grandmother's rural village after fifteen years, only to discover he has completely forgotten the girls he grew up with. As he reunites with the spirited Anzu and the beautiful Nami, he quickly falls into passionate, forbidden encounters with them. However, these relationships breach a mysterious "Taboo," hinting at a supernatural price that may plunge the village into a frozen sorrow.
Musashi discovers that his childhood friends are actually princesses of four demon clans living in a hidden spirit village. After recalling a childhood engagement ritual that bound him to all four girls, he becomes the center of a conflict between the clan chiefs and the princesses. When Mayuki's grief triggers a catastrophic freeze, Musashi saves her through intimacy, only for Mayuki to ultimately vote for his banishment to ensure he can live a normal human life.