Realistically though, how many white people would pay for a platform with all black content, one that they are told is explicitly not for them?
But they in no way market to Japanese, or Asians in general. I think that is the key.
You should be marketing "black content for everybody", not "content for black people". Sure, the segment that responds will be heavily slanted to certain demographics, but at least you aren't putting up artificial barriers, and you'll stir up a lot less upfront negative reactions.
Unless controversy is part of the marketing strategy, which is risky, but sometimes works.
Black hair products can be a thriving business, just as this potentially can be as well.