Japan isn’t a terrible place, but its legal system and police force lacks a lot of confidence. It has around a 99% conviction rate, which sounds good, but tends to be endemic of the fact that a lot of crimes are never pursued or looked at. At its worst, the conviction-hungry prosecution forges evidence or coerce confessions to feed their records.
Here’s and article focusing on assault on foreign women – police have a tendency to shrug and say “what can ya do?”
There’s also a (deliberately stylized) video game series made about the Japanese judicial system, and this article analyzes how startlingly close it is to the real thing. There’s a lot
Wikipedia also has a decent section on the justice system. Some of the sections are undercited, by they do agree with other things I’ve read. One cited section says:
Essentially, a system that places such a huge value on being sure before even beginning investigation leads to a hugely imbalanced system that resorts to coerced confessions, and outright ignoring real victims if the evidence isn’t 100% solid.
That’s not to say Japan is a hellhole, it does legitimately have a low crime rate, and maybe we can partially credit their justice system with that. Miscarriages of justice and lack of investigation happen in any system. However, everything I’ve seen indicates that reliance of “sure convictions” impedes investigation and hides true crime. I know that most Japanese people I’ve talked do don’t exactly have… confidence in their judicial system. Though admittedly polling expats is a shitty way of getting info on a country’s government.