Yukie gave birth to Shiro when she was 25. She raised him alone, but even after graduating from university, Shiro continued his part-time job and showed no signs of looking for a proper job. Shiro had no romantic interests, and in fact, he had never brought any friends home. The reason was that Shiro harbored sexual feelings towards his mother, Yukie. Realizing this, Yukie decided to have an open conversation with him and invited Shiro on a hot spring trip.
