But comparing my example with the NSU makes no sense to me, the NSU is comparable with Aum Shinrikyo (the Japanese cult that caused the sarin attack back in the 90s) in the sense that they both have/had negligible memberships compared to the countries population, i.e., a few hundreds or couple thousands members, so I don't think in either case you can generalise the behaviour of German or Japanese citizens from the existence of 100 or 1000 pieces of shit human beings.
Japan's immigration percentage is also massively different (~2%) from that of Germany, Spain, UK, or USA (each ~15%) and I'm sure that has an impact on the attitude towards foreigners too.
I completely agree though that the issues I may run into in Japan are probably going to be different and possibly less severe than those that eastern/southeastern asian people or dark-skinned people may face.