Ai-iro

A color dyed with Japanese indigo (tade-ai), which was introduced from China. Indigo is known as the oldest dye used by humankind. "Ai-iro" is also used as a general term for the colors of indigo dyeing. Hanada-iro is also dyed with indigo, and Ai-iro and Hanada-iro each have several color names given according to the depth of the color, forming groups of color names. Whereas Hanada-iro is dyed with indigo alone, Ai-iro is dyed using the Amur cork tree (kihada) as well. Its English name is "indigo."