The day of the radish sprout was established by Japan's radish sprout association on the 18th of September starting from 1986.

The reason for it being the 18th is because if you turn the 8 sideways (∞) and place the 1 below, it becomes the shape of a radish sprout.

The white radish sprout is a food item made up of the cotyledon and hypocotyl from a freshly germinated radish sprout, and is particularly rich in enzymes