Tsuukin Kairaku: Chikan de Go!! episode 1

When horny men and beautiful women cram themselves into the train for their early morning commute, all that body-to-body contact begins to take a sexual toll on the passengers. The men's casual groping quickly leads to all-out molestation. Shocked, the women are resistant at first. But there's no escape from a moving train. So it's not long before these reluctant ladies give in to their own perverted passions and go with the flow. Soon the whole train is alive with sexual energy as it drives and thrusts toward its dripping-wet destination. (Source: ANN)