Shintaro, a son who has been in love with his mother Marina for a long time, is unable to take the next step because his reason gets in the way. Meanwhile, his father returns home from a long absence from his work and unleashes his pent-up sexual desire on Marina's anal hole, while Marina, who is in the prime of her life, masturbates alone. Shintaro has no time to step in and asks his best friend for advice, but... Finally, Marina Matsumoto takes on the forbidden challenge of anal for the first time! Don't miss the sight of her feeling lustful as a thick cock is forced into her pure anus!