She is referred to as "Empress [Regnant] Iitoyo" (飯豊天皇 Iitoyo-tennō) in the Fusō Ryakuki and the Honchō Kōin Jōun-roku [ja], a 12th-century and a 15th-century collection of historical texts, respectively.

Oshiwa's sons Ōke and Oke fled to the province after his murder, but there is no information about their aunt (sister, according to the Nihon Shoki) Iitoyo during this time.

Princes Ōke and Oke were in hiding, so another suitable heir to the throne from the lineage of the Sun Goddess Amaterasu had to be sought.

According to the Kojiki, this search ended with the discovery of Princess Iitoyo at the Tsunosashi Shrine, in Oshinumi, in Kazuragi, where she conducted her political affairs.

- Jien: GukanshōIitoyo's name was entered as Empress Tsunuzashi in the list of emperors by Ernest Mason Satow in the Japanese Chronological Tables (1874).

She is also recognized as a sovereign empress on various occasions, for which information can also be found in the Nihon Shoki, where the term bō is used for her death, which is otherwise reserved exclusively for emperors.

The historian Shinobu Orikuchi sees her as the first ruling empress in the history of Japan, who combines the roles of the shaman and the sovereign.