Japan has historically been a racist country. I'm not surprised.
It's pretty obvious that the bi-racial society in Japan tells itself that constantly to avoid the conflicts that would have otherwise ensued between the Emishi and the Yayoi.
Based on tooth type it's roughly a 40/60 split and might well account for several of their many centuries of chronic warfare.
They used to take this stuff very seriously you know.
Are we about to see a ressurection of the Greater East Asia Coprosperity Sphere???