So as someone interested in Japanese culture I used to read quite a bit about expats in Japan and that also extended to occasionally reading about expats in Korea.
I think people are mistakenly calling the two equivalent. It seems to me the flavour of xenophobia is different.
There used to be a blog by a black guy in Japan that was pretty popular. He occasionally talked about the stereotyping, or staring, and occasional discrimination that occurred there . But overall, his experience is positive, he loves living there, his interactions with Japanese overall tend to be positive with some bad apples, he married someone there, etc.
In comparison, I also read a blog by a black guy in Seoul. And this guy absolutely hated his life. His entire blog ended up being almost purely about complaining about the every day treatment he would get.
The Japanese may be ignorant and naive about race relations, but they do not appear to have the maliciousness about it that seems to be prevalent in Korea.