I discuss red, yellow, green and blue according to the linguistic and historical aspect, and the research for the correspondence with color name and chromatic value.
Are this four colors inherent psychological fundamental element? If four colors are not so, then I propose the fearless hypothesis of the derivation process of the four colors.
The survey of the historical transition of the Japanese is made and aka, ao, shiro, kuro are the stabilized color names, and ki was included in aka and midori was in ao. 
The orient religions of Taoism (inyougogyou) and Vajrayana Buddhism have the fifth elements and these elements correspond the five colors. This colors are white, black, red, blue, and yellow and green is not included.
I examine the research for the correspondence with color name and chromatic value and so the distributions of green and blue are wider than these of red and yellow.
Red, yellow, green and blue is not inherent psychological fundamental element.
The fearless hypothesis of the derivation process of the four colors is that the color circle was visualized and at this circle, the four color are the transition point of the hue.

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