I live in Japan and I've read enough horror stories between the police and foreigners that I'd just like to say, don't mess with police here. They are very nice and polite, until they are not. They have been under heat multiple times for apparent human rights violations, which include indefinitely detaining people until they confess of the accused crime.

Another beautiful quirk of Japanese law is that you can be held liable for crimes even if you have absolutely nothing to do with them, just by virtue of being family of the person who committed them, like in train suicide [1] or having some (even fairly removed) family member who was in the Yakuza

[1] https://www.irishtimes.com/news/health/families-fined-for-su...