Black hair products can be a thriving business, just as this potentially can be as well.
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.
Feels like some kind of "Outrage marketing" strategy, I mean, look how this thread has blown up over the last hour. I'm sure the OP is smart and knew what they were doing when wording this post.