Caste-based discrimination was an important civil rights issue for most of the 20th century, and still has long standing effects on the organization and opportunities for people in Japanese society.
And of course there’s also Zainichi Koreans, long standing Chinese communities in places like Kanagawa, the urban rural divide, and countless more divisions that counter you’re simplistic description of Japan as a uniform society.
https://en.m.wikipedia.org/wiki/Burakumin
Caste-based discrimination was an important civil rights issue for most of the 20th century, and still has long standing effects on the organization and opportunities for people in Japanese society.
And of course there’s also Zainichi Koreans, long standing Chinese communities in places like Kanagawa, the urban rural divide, and countless more divisions that counter you’re simplistic description of Japan as a uniform society.