Thirty-Something Stepmother: Dripping with Immorality

Kimi is married to Tatsuro, who has a son, Kengo, who is the same age as her. Every night, Kengo can hear Kimi's moans coming from the bedroom, but he somehow manages to keep his sanity. Meanwhile, Kimi's childhood friend, Kaori, runs away from home after a marital quarrel and comes to stay with her.