Last week, figures released by the Metropolitan Police Department showed a leap from 96 reported cases of molesting incidents on trains in 1996 to 2201 cases in 2004.
And while there was hand-wringing at what some perceived as the growing problem of more women than ever before being interfered with, women's groups are actually upbeat about the statistics.
"We can't know for sure, but I really don't think there are more cases of these kinds of sexual harrassement than there were 20 or more years ago," Emiko Hirano, a spokeswoman for the New Japan Women's Association, said.
"What we're seeing now is more women willing to talk about it and not being scared to point to an abuser.
According to Hirano, "Even as recently as a decade or so ago, women wouldn't talk about it because they didn't want to stand out or because they didn't want to undergo police questioning.
For molesters, the morning rush
hour is the best time for thrills
"Back then, society was not as aware of women's human rights, but women today are refusing to be treated like this," she said.
"I'm sure there are many cases that are still not reported, but this is definitely a step in the right direction."
The problem of chikan, literally meaning "perverts", has become such a problem in recent years that train lines in many of Japan's cities have been considering the best way to stop the problem.
Private lines in Tokyo, Nagoya and Osaka all operate women-only carriages at certain hours of the day, including the morning rush hour, which is perhaps surprisingly one of the peak times for some molesters to get their thrills.
But it has taken a public outry for JR East, which operates the majority of the subway lines in Tokyo, to come round to the idea that something needs to be done to protect its female customers after resolutely refusing to act.
According to a spokesman for the company, JR East is considering a belated ban on men travelling in certain carriages at specified times of the day.
The Saikyo Line, linking the commuter towns of Saitama, north of Tokyo, with the centre of the city is considered one of the worst in Japan for incidents of molesting.
Previously, JR East had resisted change on the grounds that it might worsen the already severe problem of overcrowding at peak hours.
Train lines are waking up to the
complaints of female customers
Tokyo Governor Shintaro Ishihara added his voice to the chorus for action this week, saying he was "shocked" at the most recent statistics and the way in which young women appear to be most at risk.
The second time 27-year-old Makiko was molested on a train in Tokyo was even more shocking than the first incident, she says. It was the middle of the day, in a train that was not crowded, when a man with a brief case sidled up to her as she stood looking out of the door windows.
"He was a middle-aged man, in a business suit, and he clearly knew what he was doing," Makiko, who does not want her family name to appear in print, said. "He held his brief case so that it hid his free hand and he suddenly touched my bottom.
"It was very skilfully done and I'm pretty certain it was not the first time he'd done it, but I was so surprised at how blatant and bold it was that I was too shocked to act."
Makiko continued: "I quickly found a seat and sat looking directly into his face - he seemed just an ordinary man - but he didn't seem at all concerned and just got off at the next station."
None of the other passengers in the train noticed the incident and Makiko, who works for an importing company, said she felt scared of accusing the man of molesting her in case no one believed her.
Makiko thinks women-only carriages are a good way to protect women since many men do not take the issue seriously.
That was several years ago. Now Tokyo Mayor Ishihara is suggesting a series of aggressive adverts be placed inside train carriages with blunt messages such as "Chikan are our enemies" and "Let's bust the chikans".
Some lines may ban men from
travelling at certain hours
"Men here need to learn to respect women's rights, although I think that will be difficult as long as comic books and late-night television programmes continue to laugh at this sort of behaviour, encouraging it instead of trying to stop it," she said.
Hirano, the New Japan Women's Association spokesperson, was herself molested on a train as a teenager and describes the experience in an almost dismissive way.
"I was on my way to high school 25 years ago when I was the victim of sexual harrassement on a train," Hirano said. "I was afraid when it happened and even though I told my mother, I couldn't go to the police. There was just a different atmosphere back then. It was a waste of time reporting it to the police.
Today's women are not ready
to suffer molesters in silence
Hirano added, "You had to learn to be careful and go to school with your friends, but I believe that if you asked the young women then, the majority would say they had had some sort of similar experience."
There is a wide lack of awareness among men in Japan that this sort of harrassement is a human-rights abuse, and that stems from all levels of society - families, the education system and employers failing to stamp out the problem in the workplace - failing to teach right from wrong, she said.
Yet Hirano remains optimistic that a new generation of Japanese men are also aware that it is not acceptable to abuse the human rights of women.
"I think newer generations will be different and as well as not committing this sort of crime as often, they will not tolerate others doing it either," she said.