As a popular erotic novelist, Raku Torase has been making a living with his writing. He pays a visit to his best friend and owner of a hot spring inn, Gorou Torine, who he inherited it from his grandfather.
To Raku's surprise, Gorou asks for a favor. In his current novel, there is a scene involving cuckolding, and Gorou wants Raku to sleep with his wife to gain a deeper understanding of the emotions of being cuckolded.