Yoko has been married to her kind and earnest husband for 15 years, and although their marriage is ordinary, they lead a happy life. The Sasagawa couple are not blessed with children, but they Ke'ai on Yuta, the son of a single-parent family who live next door, like a child. One day, Yoko holds her saliva in the face as she overhears a conversation in the bathroom where her husband and Yuta are bathing together like father and son. "Yuta's penis has gotten so big! Must be at least 17 centimeters!?" Yoko has not had sex for three years, so there is no way she can just ignore this conversation...