Groper Train: A Married Couple Groping Together (1995)

Kiriko is getting married next year. Even though they are having pre-marital sex, she still has doubts about his love for her. One day, Kiriko is harassed in a morning rush-hour train. The attacker is surprisingly a woman... Hanae. However, from behind, another's hand reaches out... It's a man, Jotaro, and the two are married. Kiriko admires the two and wonders if they are close enough to be groping each other...