In the Nihon-shoki, it is written, 'The castle was built under the direction of exiled nobles of Kudara (Baekje, Paekche)' in the articles about Nagato-jo Castle, Ono-jo Castle (Chikuzen Province) and Kii-jo Castle.
日本書紀における長門城、大野城(筑前国)、基肄城の記事に「亡命百済貴族が築城の指導に当たった」とある。