Rie's husband Kengo and his younger brother Yuji plan a three-day, two-night trip to a hot spring inn surrounded by lush nature. Their late parents often brought the brothers here as boys, but a terrible incident now taints this cherished place. The baths switch between men and women on a schedule, and Rie walks in without realizing it is currently the men's turn. She comes face-to-face with Yuji, who sees her naked body for the first time, loses control of his desire, and attacks her.