Niizuma furin: Senaka de kanjiru yubisaki

Original title: 新妻不倫　背中で感じる指先

Rika, an office worker, married Takuya, the son of a company's president. Rika can't help but want to brag about her lifestyle to her older sister Nanako, an honor student who has always been the source of her inferiority complex since childhood. One day, Nanako, who was married to an international woman, returns to Japan after getting divorced and moves in with Rika. The three of them start living together, but...