I think this is very simple. Japanese people aren't violent anywhere.
Some races are exceedingly violent everywhere. The rates per 100,000 for murder, rape, robbery, etc seem to be very similar in every developed nation on earth. Violence is a culture issue which manifests as a racial issue on the surface. There is no cure. No amount of money will change it. The intentional destruction of the nuclear family has only made it worse, and it will only continue to get worse as morality is destroyed as our kids are sold a line of trash in the public indoctrination system they call "schools". Forced desegregation destroyed America. There's an unpopular opinion, but I don't care.