Keiko's Mambo: Molester Train Hidden Run (1981)

A wife who invites a molester to a hotel to play a honey trap, but falls in love with the molester's extraordinary sexual prowess. A newlywed married a molester who was so handsome that she fell in love with him at first sight, but is at a loss when she finds out that he only gets aroused on the train. A university student who likes masturbating accidentally meets the nude model he always masturbates to on the train. A wife who brings various adult toys onto the train to cure her husband's impotence, has the molester use them, and shows them to her husband.