At this time, the way of imperial succession was to change from the form of elder brother to little brother succession to the form of father to son succession, and when the practice of succession between the direct line male children, from Tenmu to Kusakabe, Monmu, and Shomu, had faced with difficulties due to a series of young successors' deaths, it was sustained by the substitutional empresses, Jito, Genmei, and Gensho.
この時代は兄弟継承から父子直系の継承へと皇位継承方法が切り替わる時期にあたっており、相次ぐ早逝によって危ぶまれた天武・草壁・文武・聖武という男子直系の継承が、持統・元明・元正という中継ぎ女帝によって支えられた。