But male passengers are hitting back, asking for men-only carriages, too.

Shareholders of Seibu Holdings, which runs trains in the Tokyo area, have petitioned for carriages reserved for men.

"There have been many cases of groping, as well as false charges of groping," the shareholders said, asking for a vote at the company's annual meeting.

"While measures against groping, such as setting women-only carriages, have been effective to a certain extent, no measures have been taken against false charges of groping... In the spirit of gender-equality, a male-only carriage must be introduced."

False accusations of groping were in the spotlight when Japan's Supreme Court recently overturned the conviction of a professor for groping a girl on a Tokyo train.

But the request for men's carriages may not be implemented, as Seibu's board of directors opposes the idea. "The reality is we have few requests from Seibu Railway users for setting up male-only carriages," a spokesman said.

In Tokyo, around 2,000 people were arrested for groping in 2007.