Moon viewing festival
China and Japan have had the custom of appreciating the moon since ancient times.
In Japan it is said that the custom has existed since the Jomon period, before a large number of people from Eurasian continent moved into Japan in Yayoi period (300BC-300AD).
Interestingly, the highest ranking deity in Shintoism (according to the Japanese mythology) is, AMATERASU (天照大御神）, who is the sun goddess. And one of her brother is "Tsukuyomi-no-mikoto"（月読命）,
whose name includes the word, "月”, which is "moon".
Japan used to use lunar calendar for a long time, before introduction of the Gregorian calendar (Solar calendar) in 1872 by the Meiji government. Lunar calendar had been closely related to the seasonal festivities, customs and traditions of the Japanese people. This sudden change of the calendar was one of a forceful policy that influenced the lives of the Japanese during the time of modernization, Westernization, as well as militarization.
A official custom of moon viewing was introduced from China around the Heian period (9th century) . The nobles and imperial families in Kyoto had Kangetsu, or moon viewing and boating parties (to enjoy the reflection of the moon swinging on the water surface from a boat, instead of viewing the moon directly) in which they would compose poems and enjoy drinking sake.
Since the autumn full moon time matches with the time of rice harvesting, traditionally, many autumn festivals are held at local shinto shrines to show gratitude to kami.
I went to one at my favorite shrine, Ohmiwa shrine. It was quite magnificent with live court music and ceremonial dance by the shrine maidens.