In the following year, 665, he ordered to build Kodai Sanjo (ancient Korean-style mountain castles) from Northern Kyushu to the coast of the Inland Sea including Ono-jo Castle (Chikuzen Province), Kii-jo Castle and Nagatonoki Castle.
翌665年には北九州から瀬戸内海沿岸にかけて大野城(筑前国)、基肄城、長門城などの古代山城（朝鮮式山城）を築かせた。