It is said to symbolize the brilliance of the sun with a dark reddish yellow made by layering Suozome and Shikonzome dyeing on Kihazezome.

It is the color of the haze worn by the emperor at the ceremony of haru, and it is the color called absolute prohibition, which is the strictest of the forbidden colors.

In the Heian period law collection "Enki Shiki", there is a description of "Yellow Ash Aya Ichibi, Sashi Fourteen Loaves, Su Fang 11 Loaves, Vinegar 2 Sho, Ash 3 Axes, and Firewood Eight Loads", and it can be seen that "Fourteen Loaves, Eleven Loaves of Sufang, Two Loaves of Vinegar, Three Ashes, and Eight Loads of Firewood" were used to dye Aya Ichibi in yellow oak dyeing.