Motohashi runs an osteopathic clinic, and his wife has finally become pregnant. His wife's younger sister, Miwako, has started to visit frequently. Miwako's husband is working away from home, but for some reason she remains in Tokyo. Motohashi is Kokoro to see that Miwako, who until recently had a childish look, has transformed into a grown-up woman. One day, when Motohashi goes outside the clinic to have a smoke, he sees Miwako and Takashi, an employee, embracing each other. Curious, Motohashi borrows a security camera and decides to peek into Miwako's daily life, but...