Netorare Chikan Densha ~Kanjousen~

Michihiro Kai has just gotten himself a girlfriend named Meguru. They meet at the station every morning and take the train to school together. One day, however, the rush hour crowd is too much, and the couple gets separated.

That's when Meguru runs afoul of a molester... while Kai watches, unable to move! Eventually, Meguru even gets violated in her most delicate of areas...

No matter what happens, she just can't stop getting molested!

[From DLsite English]