Thank you. I can't say it surprises me that Japanese from Zero oversimplified, though I've seen the same point made elsewhere. I appreciate the extra information, though - especially the poetry and the bit about crayons in your last link.

It's precisely because colour divisions are arbitrary in themselves (inasmuch as the spectrum has no sharp divides) that the baggage they pick up as they travel the world is so visible and so clearly culturally derived. For witness whereof, we need look no further than "white" and "black" (or "coffee-colour versus pinko-grey" as Forster put it in A Passage to India) as applied to people. A fascinating subject.