Imperial Prince Osabe (the great-great-grandson of Prince Kusakabe), who was the son of Imperial Princess Inoe (a daughter of Emperor Temmu), a older sister of Imperial Princess Fuwa, and Shirakabe no okimi (Prince Shirakabe, later Emperor Konin), was formally installed as Crown Prince as the symbol of merger of Tenchi and Temmu Imperial Line at the time of enthronement of his father, with demise of his aunt, Empress Koken Empress Shotoku.
不破内親王の姉の井上内親王（聖武天皇の娘）と白壁王（後の光仁天皇）との間の子である他戸親王(草壁皇子の玄孫)が、伯母の孝謙天皇称徳天皇が崩御に伴い、父王が即位した時に天智・天武皇統融合の象徴として立太子された。