The Senior SEX: Rika, who works at the Silver Welfare Volunteer Shirayuri Association office, has a boyfriend, Kaname, but recently they have been keeping their distance because he is too unreliable. One day, her co-worker Sachie, who is dating a man 40 years older than her, encourages her, saying, "Grandpas are nice. Why don't you find one for Rika at our place?" One day, when Rika is about to be attacked by Kaname, she is saved by Owada, who she was taking care of. Rika gradually begins to be attracted to Owada...