I'm just going to quote all of this because it's a lot, and you're still not quite grasping why people are finding it a problem, and are instead brushing it off.
Here is mention of chikan, or sexual harassment on trains from the beginning of this year,
something even more recent from earlier this month about chikan, and another on
how often it happens - can't find a publish date, which is frustrating, but if a news article from this month is mentioning a push to end it or make people feel comfortable on reporting it, it's still a valid resource at this point, which is incredibly sad. Japan's take of "if we don't see it, it's not happening' isn't really a great take to defend, either, just saying, especially when more and more of the younger generations are going "this isn't great". They even recently
OK'd a bill to pass in which makes the listed even more illegal than before for things like upskirting or whatnot... things that were common tropes in anime for the "loveable pervert" trope, and for good measure,
the sharp rise of it as reported earlier in the year. "That's a small number" but as the other articles say, a lot of people don't report it - sounds quite familiar, as it's the same in the US. Not being taken seriously, nothing being done about it, or the least amount of things done about it is what keeps people (both men and women) from reporting a rape or other sexual assault. For people who have had this happen to them, someone being that forward can bring back traumatic memories, whether you believe it or not, because it can be how it happened to them, or similar enough that it makes them uncomfortable.