When Sayuri and her two sons find out that her younger sister Hitomi is self-conscious about her plain appearance, they decide to take matters into their own hands and transform her into a Takumi. Lo and behold, Hitomi becomes incredibly beautiful and gains confidence in herself. However, this leads to Hitomi making advances on her sons. Sayuri gets angry, but she is soon drawn to Hitomi's beauty and they end up having sex. The four of them then step into a dizzying incestuous relationship, with Hitomi at the center.