A man with nothing to lose has no fear.
The protagonist is working a dead-end, stressful job, and has no prospects or interests in life.
Except one thing, his one and only joy in life...molesting girls on the train.
However, one morning, a busty gal catches him, and the gig is up.
Now, he has lost even his job, and he has nothing left.
All that remains...is to exact his molesting revenge upon her!

[From DLsite]