I've heard that the justice system in Japan is absolute trash. Not only are many laws regarding things like recreational drug possession insanely punitive, they have a general conviction rate over 99%. Which is a major red flag imo. Makes you wonder how many people there have been wrongly convicted in order to keep the numbers up.
More info:
https://www.vox.com/world/2015/12/13/9989250/japan-crime-conviction-rate
https://pursuit.unimelb.edu.au/articles/japan-s-hidden-landscape-of-violent-crime