There are plenty of people who hate other people for various reasons. We have a hot war with hundreds of thousands of people right in now in Europe, without any racial component involved. I fail to see how this provides any justification for racism though.
Yes, Japan is a very high-conforming and ethnically homogeneous society. It is also a low-crime society. However, to derive just from that that absence of racial homogeneity alone leads to high crime makes no more sense than claiming that not using logographic scripts leads to violence - since Asian society are generally less violent than, for example, the US. You need to do much more work than just picking one difference and attribute everything to it.
Yes, Japan is a very high-conforming and ethnically homogeneous society. It is also a low-crime society. However, to derive just from that that absence of racial homogeneity alone leads to high crime makes no more sense than claiming that not using logographic scripts leads to violence - since Asian society are generally less violent than, for example, the US. You need to do much more work than just picking one difference and attribute everything to it.