Today I'm going to rape my brother's wife.

Mao is a wife who lives a happy life with her husband Toshio, a private practitioner. One night, Toshio's younger brother, Shingo, suddenly came to the Hamasaki family. In contrast to Toshio, who casually says, "He's a free man, so just leave him alone," Mao is twitched at Shingo's words and actions and is unable to control his anxiety. This is because Shingo knows Mao's past secrets. Mao's anxiety changes to reality. Shingo threatens him with, "You don't want Mao's past to be found out about her older brother, right?"