I'm not saying this, because I'm not aware of this. I have a friend who is enjoying living in Osaka, but I wouldn't feel qualified to talk about Japanese sentiment towards him or any other group of non-natives.

I'm saying that culture spreads through fear of being ostracized and the cost of not conforming to that culture. This is true in any country. It seems Japan has a "broader" and "firmer" culture that is rooted in respect to others, but it would take some serious effort for a similar culture to take hold in Europe or the US, I think.

A sense of "non conformity" leading to issues is not unique to Japan though, in Europe it is described as a problem with "multiculturalism".

The British (of which I am one), have spent thousands of years stealing the best bits of immigrant culture but seem to have forgotten that (or have been unable to absorb, for whatever reason), for the last ~60 years. That's leading to a rise in far-right sentiment and a growing desire for mono-culturalism. I can see evidence of that in Germany, France and other European nations. I could easily imagine it appearing more in Japan.

This is the flip side of East Asian societies where everything is polite and orderly: they're also extremely conformist (sometimes stifling so), and the conformity and good manners are maintained by strict social policing (it's not much fun to stand out and be different)