Crunchyroll keeps getting mentioned here, as a success story. Certainly, they focus nearly exclusively on Japanese content.

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.