丹後國
The story itself can be found in much older sources, dating to the 8th century (the Nara period), where the protagonist is styled either "Urashima no ko" or "Ura (no) Shimako", attested in earlier sources such as the "Fudoki" for Tango Province () that survived in excerpts, the "Man'yōshū" and the "Nihon Shoki".