Red (赤/あか aka \ レッド, reddo) is one of the three primary colors of light and is also used as a proxy for magenta.
It is defined as 0° (origin) in the RGB and HSV color circle.
The culture and impressions associated with the color red are generally widespread, and in many cultures it is used in the vocabulary with images such as gorgeous, prominent, beautiful, clear, and intense.
The color red itself is often associated with the main character in Super Sentai, regardless of gender or generation. It has been consistently used as the main character's color until it was discontinued in this work. There are also many pink main characters made by mixing red and white in works for girls.
Since it was the symbolic color of the Soviet Union (actually closer to vermilion), it is also treated as a symbolic color of communism and socialism.
Even today, communist countries such as the People's Republic of China and Vietnam still use red as the color of their flags.