Jun went to play with other friends at his friend Shota's house. There, she accidentally witnesses Shota's mother Ria masturbating while calling her cheating partner. Jun, who was worried about her Ria, was surprised, but she could not suppress her young sexual urges due to Ria's unpleasant appearance, and threatened her to reveal her cheating. Not wanting only her son to know, Ria makes a deal with her Jun, but she misreads the magnitude of her desire for her. Ria's days of frenzy with no end in sight begin.
