Kinensai
Kinensai is a festival that was celebrated every year in ancient Japan on February 4th. It was an important observance of the government. It was held to pray for a good harvest. Emperor Tenmu started the festival in 675 as a rite of the Japanese government. He required all the shrines recorded in the Jinmyocho to perform it.
During the festival, tribute was offered to the gods, and the ceremony was attended by high-ranking officials, but the emperor himself did not participate. In the Heian period, the festival became a mere formality and was celebrated solely within the Department of Divinities, the body responsible for the governance of Shinto affairs by the government.
Later, the festival became more solemn and focused on worshipping Amaterasu Omikami, the sun goddess, and during the period of "cloistered emperors", it became a rite performed by the emperor himself to honor Amaterasu. Kinensai eventually became such a sacred ceremony that it would be canceled in case of any pollution at the Ise Shrines.
However, the festival died out at the end of the Muromachi period due to military conflict. It was later revived in an abbreviated, irregular form called sairo by the Shirakawa house, which had inherited the position of head of the Department of Divinities. Kinensai was not reintroduced until the Meiji period in 1869.
It is sometimes contrasted with or the fall festival.
References
Shinto