Mao is a wife living a happy life with her husband Toshio, who is a practicing physician. One night, Toshio's younger brother, Shingo, suddenly comes to the Hamasaki household. In contrast to Toshio, who brushes him off by saying, "He's a free spirit, so we should just leave him alone," Mao is nervous about Shingo's words and actions and cannot contain her anxiety. This is because Shingo knows a secret about Mao's past. Mao's anxiety soon becomes reality. Shingo threatens her, saying, "You don't want your brother to know about Mao's past, do you?"...