Autumnal Equinox Day, known in Japan as 'Shūbun no Hi', is a public holiday that marks the arrival of fall. It is celebrated annually around September 22 or 23, when the sun is exactly above the equator, and day and night are of almost equal length. Historically, it was a time for the Japanese to thank their deities for the summer harvest and prepare for the winter season.

As a part of the Shinto religion and Japanese tradition, the Autumnal Equinox Day is a time when people pay respects to their ancestors. Many Japanese visit family graves, cleaning the gravestones and offering food, incense, and prayers to the spirits of the departed. These offerings are made in the belief that the spirits return during the equinox to provide blessings.

Autumnal Equinox Day in Japan is also associated with the beauty of nature, as the changing colours of the leaves (koyo) bring a picturesque backdrop to the festivities. It marks the beginning of koyo season for much of the country, a time when the Japanese maples and ginkgo trees turn bright shades of yellow, orange, red and brown. Many people participate in 'momijigari', the traditional viewing of these stunning autumn colours.