I've heard about this many times before but how prevalent is this actually today? It's hard to be racist if it requires detailed ancestry analysis. I've never h

I've heard about this many times before but how prevalent is this actually today? It's hard to be racist if it requires detailed ancestry analysis. I've never heard it mentioned in Japanese media. The only ways I could imagine it occurring is maybe trying to join big old Japanese companies (but a background check of that nature seems like it would still be - legally? - difficult) or perhaps marriage into a super traditional home which there can't be many of now.