Tokyo Train Girls 4 - Young Wife's Desires (2009) - Tadashi Kyouya

IMDB says:
House-wife Akiko learns of her husband's affair with her former co-worker.

Tokyo Train Girls 3 - The Sensuous Nurse (2009) - Tadashi Kyouya

from amazon:
Super conservative beautiful maiden Asuka Io in her first original video appearance! A new nurse is stripped of her white uniform and is made to experience sexual indignities. Chinatsu Izawa, the gorgeous actress with the beautiful legs, plays the older supervising nurse. The molestation and white uniformed nurse play by the finest actresses will challenge and stimulate the minds of men all over!

Tokyo Train Girls 1: Private Lessons (2009) - Tadashi Kyouya

IMDB :
New teacher Chihiro has been on the job for three months. She does her job with great enthusiasm, but she has a secret that nobody must know. As a student, she accumulated debt in order to keep up with her well-to-do friends. She can't pay it back on the wages of a teacher so she started working part-time as a Chat-Lady. In front of a web camera that hides her face, she shakes her breasts and hips. By chance, her student, Kazuaki discovers the web site.
- Written by lament

Tokyo Train Girls 2 - Supervixen (2009) - Tadashi Kyouya

IMDB:
Ayumi is married to Yukinari, a man with some serious sexual perversions. He enjoys molesting his wife on the train, engaging in some light bondage and blindfold sex sessions with her. He's also been sleeping with Kazuha (who happens to be Ayumi's friend) on the side. Eventually he even hires a man to rape his wife while he secretly records (and enjoys) the action. A lot of sexual manipulation ensues and at the end it's a twist to see who's been playing whom.
- Written by J_Charles