The Japanese autumn ceremony that historically marked the emperor’s first offering of newly harvested rice is Daijō-sai.
Daijō-sai, also written Daijosai, is the first Niiname-sai ceremony performed by a newly enthroned emperor of Japan. During it, the emperor offers newly harvested rice and other foods to the imperial deities, especially Amaterasu and Toyouke-Ōmikami, and symbolically shares the offerings with them.
The ceremony is connected with imperial succession and is held once for each emperor, unlike the annual Niiname-sai ritual. It forms part of the enthronement-related observances and is generally conducted in November after the autumn harvest.
Daijō-sai is sometimes confused with Niiname-sai because both involve newly harvested rice and offerings to deities. The key distinction is frequency: Niiname-sai is annual, whereas Daijō-sai is the special first harvest rite of a new emperor.