People are snarking you but this is absolutely true. I know multiple people that went over in their 20s. All but one came back within 10 years. People are very polite, but it's also clear there's a sort of invisible force field always around you that drastically limits your professional options beyond english translation/tutoring work. Forming a social network is nearly impossible.

One of my friends born there did his undergrad and masters in aerospace engineering in the US as there's a lot more programs and jobs here. When he went back due to family obligations he discovered he wouldn't be able to get a job beyond translating manuals. He's been told over and over again that if he had to leave Japan for school then clearly something must be wrong with him. So besides the undercurrent of racism, similar problems are found by native born citizens that don't conform to these expectations.

> immigrants are always second-class citizens

That is true for every country on the planet.

Indeed, that is the entire point of "citizen" status.

I don't think you understood that statement. It means you'll never be treated like "one of us" regardless of your passport and visa status.