It isn't as if every one of those extremists is focused on the local ethnic minorities, however. There are people in rural America who hate Muslims even while their populations are slim-to-none in those areas. Tojo isn't an in-person political activist, he's a guy in Japan who found his way to these ideas through the internet. I feel that to be an entirely realistic explanation.
Also, no actual Japanese person would hate Native-Americans or "Hispanics" (a racial concept which doesn't even exist outside of America).