In the late 660s, Emperor Tenchi who transferred the capital to Omi no miya had originally designated his younger maternal half-brother Prince Oama as Crown Prince (according to the Nihonshoki [Chronicles of Japan], the younger brother of an Emperor. And also there is a theory that the story of Prince Oama was designated as heir was itself a fiction in the Nihonshoki) but on November 26, 671, he designated his own son Prince Otomo as Daijo-daijin (Grand minister of state) beginning to show his will to let Prince Otomo succeed to the throne.
660年代後半、都を近江宮へ移していた天智天皇は同母弟の大海人皇子を皇太子（日本書紀には「皇太弟」とある。また、大海人皇子の立太子そのものを日本書紀の創作とする説もある）に立てていたが天智天皇10年10月17日(旧暦)（671年11月26日）、自身の皇子である大友皇子を太政大臣につけて後継とする意思をみせ始めた。