Mariko, who has been a little disgusted with her peculiar propensity while spending calm days with her husband. Kenta, a playboy's brother-in-law, sees through her secret frustration. Mariko is persuaded by Kenta, who skillfully pokes at Sukehira's deep-seated heart, and surrenders herself to his fingertips as if being carried away. A delicate and bold caress easily melts her vaginal wall and gradually unravels her stubborn mind and body. At some point, Mariko tells herself, "I'm just being naive...".