Here is something strange about Japan that i did not know:
Why do Japanese people say that they have blue traffic lights when they are really green?
This is because historically, Japanese people considered green to be a shade of blue. For example, the Chinese character for blue, pronounced ao is made up of two characters, iki (life) and i (well) and refers to the colour of plants which grow around a well, a colour between green and blue. When Chinese people see the character, they say it means green, but Japanese people say it means blue. Japanese books on colours tell us that there are four tertiary colours: red, blue, white and black, and that all others are shades of those four main ones. Ao, therefore, is a sort of ideal blue, halfway between green and blue. The sky is said to be blue, but it is a different shade of ao than a traffic light is. Tree leaves are said to be green, but green is a shade of ao, like crimson is a shade of red.
In another interesting cultural difference relating to colour, Japanese children always colour the sun red instead of yellow.
So the four primary colors are; red, blue, black and white. I can almost see that, besides yellow not really fitting in anywhere...