.•✬[]✬•. Train (Station) .•✬[]✬•.

http://www.mangago.me/read-manga/himitsu_no_kuchizuke/an/himitsu-no-kuchizuke-chapter-3.html/2/
Threesome on the train - Actually the two guys who end up together already knew each other but their love blooms on the train and the other guy helped them to get together. Anyway they work together on the train so they met there.

Another threesome on the train with Iijima-san. The two other guys who end up together didn't know each other: their relationship starts with molestation on the train.

Jin notices a guy being molested on the train and it happens that they are actually classmates.

http://www.mangago.me/read-manga/junai_ni_torawarete/ms/online_manga/6851-4.html/7/
Story about a salaryman and his molester on the train.

Mizuki gets molested on the train by a guy who happens to be the president of the student council.

Story about a working man, who always falls for straight guys, and a train conductor.

http://www.mangago.me/read-manga/shinshi_to_norainu/bt/manga/shinshi_to_norainu/c006/pg-3/ (Chapters 6 & 7)

http://www.mangago.me/read-manga/yajirushi/bt/mi_chapter-4/pg-1/
Plot twist - This one is a bit difficult to define cause I don't really know how their relationship evolved after the story ended, if they eventually fell in love or not. All I can say is that there is a student who is molested on the train and he was seen by a guy who happens to be a classmate. (This one is really twisted - Beware of rape)

Inside a crowded train, Yuma takes a peek at someone else’s cellphone...