Niinamesai (Niiname no matsuri, Shinjosai) is a ritual held each November 23, in which the Emperor offers newly harvested rice to the deities of heaven and earth, eats it and expresses gratitude for the harvest. It is held at Shinka-den Shrine, which is located near to Kyuchu-sanden (the Three Shrines in the Imperial Court).
It is a ritual of rice farming held in the autumn, at which the Emperor worships deities by offering newly harvested rice.
It has been passed down that Niinamesai was first held in the Asuka period, during the reign of Emperor Kogyoku.
Although suspended for some time, it was revived in the Genroku era (1688 - 1703) during the reign of Emperor Higashiyama. Prior to the adoption of the solar calendar in 1873, it was customarily held on the second U no hi (day of the rabbit) in November (lunar calendar).
The day of Niinamesai was a national holiday during the period from 1873 to 1947.
After World War Ⅱ, November 23 was designated as a national holiday called Labor Thanksgiving Day.
Since then, Niinamesai has become a ritual of Ise-jingu Shrine and its related shrines, and on that day the Emperor's messenger is dispatched to Ise-jingu Shrine and offers Omike (food for deities).