It is said that the old days meant bright and obvious things. And even if used as a color name, it seems to have been used to show the tendency of color rather than correspond to a single color. Red is said to be easy to see because it is a strong stimulus. Because of this association, the content of the symbol, etc., it is used as a sign indicating “stop” of traffic signals, or used for fire-related equipment. Japanese says “Aka” “Seki”. > colors stock
