After losing her parents, Yuzu lives with her older sister and her husband. One day, her older sister asks her to give birth to her husband's child instead of her, as she is having difficulty conceiving. After much conflict, Yuzu decides to have a child with her brother-in-law in order to fulfill her sister's wish. However, as if to betray the feelings of the sisters, her brother-in-law becomes obsessed with having creampie sex with Yuzu. Gradually, a change of heart begins to take place in Yuzu's Kokoro...