It will be interesting to see how Japan deals with it culturally. From folks I know who lived there they said that while everyone was nice, it was always clear that they were very much outsiders.
I spend a fair amount of time in Tokyo for work, and I'd say this is accurate.
My 日本語 is far from fluent, but it's frequently better than the English being spoken by random people on the street... yet it will take a good 20-30 seconds of me replying in Japanese before they'll switch away from English.
A co-worker is from Poland, and he married a Japanese woman. Their children speak Japanese and Polish at home, and only a little bit of English. Despite being very obviously half Japanese, he says the kids frequently have trouble getting strangers to speak to them in Japanese, despite it being by far their most fluent language.
This sort of thing probably doesn't sound like a huge deal to someone who hasn't experienced it, but every day to day interaction is a frequent reminder that you're not Japanese and you won't ever be - without radical change, those kids are going to spend their whole lives with their fellow Japanese citizens defaulting to the assumption that they can't even speak their mother tongue.
I still love the city and the people - they are genuinely wonderful and incredibly nice. Many of my co-workers have invited me into their homes, had me meet their families, and gone out of their ways to make sure I have a wonderful time in the city. I've had to modify my own behavior there to not accidentally make people feel like they should be going out of their way to help me, etc. And it's a wonderfully safe place, with kids expected to be able to function independently for means of getting to school, etc. There's an emphasis on personal responsibility, even at a young age, that I think is sorely missing in much of the western world these days, with helicopter parenting, etc., being so widespread.
I don't know if the whole outsider thing will change in my lifetime - but it changing is going to require more immigration, and the native Japanese becoming more exposed to foreigners who have immigrated instead of just tourists, or the breed of expats that keep to themselves in their luxury condos in Roppongi.
I've kind of rambled here, so I guess the cliff notes version is: Japanese people in my experience have been unfailingly nice, outside of some very isolated incidents of obvious racism, but yes, even people born in Japan if they look foreign will be treated as outsiders. That changing is going to require immigration opening up.