Before the Edo period, there was no law that determined the order in line to succession to the Imperial throne such as Imperial House Act, and Chokun, or the Crown Prince, was customarily chosen from among plural candidates, intervened by the will of the Emperor and by the court and bakufu (shogunate).
儲君に関しては、江戸時代までは皇室典範のような皇位継承の順序を定めた法律がなく、天皇の意思や朝廷、幕府などの介入により、複数の候補者から選ばれるのが慣例であった。