Princess Sarara of Uno

... means that when the emperor is not in power, a member of the imperial family governs on his behalf. Since ancient times, the first example of a person acting as the emperor was when, after the death of Emperor Seinei, Prince Oke (Emperor Ninken) and Prince Oke (Emperor Kenso) abdicated and did not ascend to the throne, while his elder sister Princess Iitoyoao governed the country. This was followed by three other examples: after the death of Emperor Saimei, Crown Prince Nakano Oe governed for three years; and after the death of Emperor Tenmu, Empress Uno Sararahime governed for three years. According to the Nihon Shoki, after Emperor Chuai's death, while Emperor Ojin had not yet ascended to the throne, Empress Jingu took charge of government affairs as a regent. However, since a regent is a member of the imperial family who governs on behalf of the emperor while he is in power, Empress Jingu's form of rule was more of a shosei than a seisho.

*Some of the terminology explanations that refer to "Uchinosararahime" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…天皇の在位しないとき，皇族が天皇に代わって政治を執ることをいう。古来，称制の事例は，清寧天皇の没後に億計（おけ）(仁賢天皇)，弘計（おけ）(顕宗天皇)両皇子が互いに辞譲して皇位につかなかった間，姉の飯豊青（いいとよあお）皇女が政務を執ったのを初例とし，ついで斉明天皇の没後，皇太子中大兄皇子が3年間称制した例，天武天皇の没後，皇后鸕野讃良（うののさらら）媛(持統天皇)が同じく3年間政務を執った例の3例がある。ところで《日本書紀》によると，仲哀天皇没後，応神天皇のまだ即位しない間，神功皇后が政務を執ったのを摂政とするが，摂政は天皇の在位しているときに，皇族等が天皇に代わって政治を執るのをいうことからすると，神功皇后の統治形態は摂政よりも称制に当たる。…

※「鸕野讃良媛」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報