I researched what to eat on the Autumn Equinox. On the day of the autumnal equinox, there is a custom of eating ohagi. Ohagi has been eaten for a long time as an ceremonial food on the day of the autumnal equinox, which is the midday of the equinox. The reason why people eat ohagi is because the red color of the red beans is thought to have a talismanic effect, so they can be offered to the ancestors, and because the red beans used to make the ohagi filling are in season. Since it is autumn, it is also popular as an offering.
My recommended spot for autumn leaves is Yoyogi Park. There's nothing better than sitting on a bench in a large park in Tokyo, looking at the autumn leaves, and eating meat buns you bought at a convenience store. If you are interested, check out this site!