Even the worst interpretation dates the saying back to 1870. I promise I didn't make it up, and it's common enough to be immediately searchable. Like any proverb or saying, existing doesn't make it fact. It may not be authentically Japanese, though it is listed in multiple places as a Japanese Proverb. Give it as much or as little value as you think it warrants.

Given that it distracts from my main point that every group of Europeans, especially the Portuguese and the Jesuits would have had Black people (probably slaves) with them. I'll remove the proverb and replace the subtitle. I also made it a point to say the Ainu were not Black, as many felt it was inferred.