A few months after her marriage, Haru Shibasaki moves to her husband's hometown, a cold village, due to her grandmother-in-law's poor health. Although Haru is confused by the unique rules, she tries to fit in with the village, but on the night of the couple's housewarming party, she is attacked by her husband's senior couple. As a result of this, Haru comes to know about the existence of a terrifying "fornication" that has been passed down from generation to generation in the village.
