Ryoko was soothing Tatsuya's body, who was tired from studying, in the bath every time she wanted to pass the exam for her only son, Tatsuya. One day, without warning, the bath in the house breaks down. Ryoko is surprised to learn that the gas man who came to repair her was Tatsuya's classmate, Nakajima. …. Mother and child she bathes with her again that evening. However, Tatsuya senses that Ryoko's behavior is unusual.