Natori Keiko, a housewife who lives a happily married life, begins to suspect that he and her friend Yuka are having an affair because she saw her husband Shinichi's cell phone.However, in fact, Shinichi's affair partner is not Yuka...The person who has a tryst with Shinichi every night is Shiho, Keiko's sister who has complete trust in her and will always be by my side...

“My happiness is to see my sister in misfortune”——Shiho has been disgusted with top student Keiko since he was a child.She wanted to break her sister's perfect smile... because of this, she took away the most important things from Keiko.However, only Shinichi is serious... Despite this, he acquiesced in marrying Keiko in order to knock Keiko down from the peak of happiness...

Keiko, who had no idea about this and completely believed in her sister, "I always have Shiho's help", believed Shiho's fabrication of Shinichi and Yuka's affair as true, and questioned the innocent Yuka... Then as Shiho expected, Keiko lost herThe most important friend——

In order to see the hurt look of the sister I hate the most... I fell from the peak of happiness! The poisonous fangs of the sister who went out of her way attacked Keiko!!