Aside from the social situation, it's also extremely hard to naturalize as a legal process. It's possible but no small feat. One has to be fully fluent in Jap

Aside from the social situation, it's also extremely hard to naturalize as a legal process. It's possible but no small feat. One has to be fully fluent in Japanese, reside in Japan for at least a decade, adopt a Japanese-compatible name written in Japanese characters, renounce their other citizenships, and just generally fully assimilate. Only a few thousand per year bother. There's actually hundreds of thousands of eligible long-term residents in Japan who could acquire citizenship on paper, but the criteria (particularly the renunciation of other citizenships) are burdensome enough that even some people born in Japan who have lived there their whole lives who could become citizens opt not to.