Emperor Yūryaku
In the "Nihon Shoki", Urashimako of Mizunoe is mentioned in the entry for Autumn, 7th month the 22nd year of reign of Emperor Yūryaku. Aston's translation assigns this the year 478 A.D. The entry states that Urashimako (child Urashima, child of Urashima, etc.) of Mizunoe while fishing on a boat, caught a turtle which transformed into a woman. They went into the sea, and reached Mount Hōrai (glossed in "kana" as Tokoyo), where they saw .