>>510982990 (OP)Japan just needs an immigration standard, like how high level schools have strict admissions.
1) Language ability (language school visa being a basic test of merit that supports human equality)
2) Acceptance of Japanese high cultural standards. Before permanent residency, high standard for personal behavior. 3 strikes you're out rule for disorderly conduct.
3) Willingness to assimilate. Japan supports free religion, but immigrants must make accommodations for Japan, not the other way around. Immigrant groups that agitate too much for accommodations, arguing that Japan must change, may face long term (10 year) blanket bans of that country.
4) Assimilation protocol. If any immigrant groups concentrates too much in isolated communities, then immigration levels for that country will be throttled back. Immigration levels will be kept in parity, so if there are X Indians, then only once there are X Americans etc. will Indian immigration expand. Exceptions can be made for historic groups of immigrants like Dutch, Koreans or Chinese.