>>41075There's an hypothesis that Western Europe selected genetically against personal violence through centuries of death penalty, where almost 1% of the males in each generation were executed. Of course it didn't get rid of every case, and it's possible that whites who left Europe before the cultural perception of capital punishment fully changed would still be more violent, as in mostly the ones in America being worse than the ones in Europe. I've heard that one of the authors of this research wrote a book where he makes some similar or equivalent speculation about the Chinese, except it would be throughout a much longer time period, and might explain the orderliness and conformism of East Asian cultures.
I do think whites would be detrimental do Japan, but in another way. Using the Big 5 model of personality traits, it's possible that whites are excessively open to experience. About the rest of East Asia, I'd still be cautious. I'm not that much of an extremist and I believe one or two blacks or Arabs at a time might be assimilated, the problem is always mass immigration, and that might be an issue even for Koreans or Chinese. Ideally Japan would close itself for a few years. The economic results might be temporarily disastrous, but not nearly as a bad as the devastation of losing the last war, and nothing that they couldn't manage in a few more years.