Shuri Yamaguchi lost her husband and was living alone with her daughter. Last year, her daughter got married, and now Shuri lives with the newlywed couple. The young couple used to make love upstairs, but when the sounds stopped, Shuri began feeling depressed. One day, she learned her son-in-law lacked confidence, believing he was bad in bed, and had stopped initiating intimacy with his wife. Shuri suggested, "Want me to check if you're really that bad?" and ended up sleeping with him. Though she intended it to be a one-time encounter, her relationship with him has since grown deeper and more intense.