A married woman's obscene kiss and sexual intercourse: A step-sister falls into passionate oral sex with her brother-in-law

Yuka is a married woman who lives with her husband and brother-in-law Mamoru. One day, Mamoru, who continues to be an unsuccessful actor, finally passes the audition for the stage play. However, Yuka says to Mamoru, a shy man who is troubled by the "kissing scene," and kisses him, "I'll go with you during the rehearsal." Yuka, who has become obsessed with Mamoru's intense kissing, knowing that she doesn't know how to do it, begins to stretch her tongue out and entangle her. Since then, the show begins with the two of them kissing Mamoru, telling themselves that it's because they're practicing acting.