Yosotarashihime was the Empress of Emperor Kosho, one of the eight emperors who reigned during the Kesshi-Hachidai (Eight Undocumented Sovereigns). She was the real mother of Emperor Koan and Amatarashihikokuni oshihito no mikoto.
In "Kojiki" (The Records of Ancient Matters), she is mentioned as Yosotarahime (余曾多本毘娘), who was a younger sister of Okitsuyoso, an ancestor of the Owari no Muraji. According to the main text of "Nihonshoki" (Chronicles of Japan), she is mentioned as Yosotarashihime, who was a daughter of Okitsuyoso, an ancestor of the Owari no Muraji.
The first addendum to the Nihonshoki mentions the Empress is Nunakihime, who was a daughter of Shiki no Agatanonushi Hae, while the second addendum describes her as Oihime, who was a daughter of Wakoku Toyoakisadahime.