The Onie no matsuri Festival is the first Niiname-sai Festival (ceremonial offering by a emperor of newly-harvested rice to the deities) solemnized by an emperor after his or her Sokui no rei (ceremony of enthronement).
大嘗祭（おおにえのまつり）は、天皇が即位の礼の後、初めて行う新嘗祭。