Miyake Odoi was built as the Masuda clan’s headquarter by the 11th lord Kanemi in the 14th century.

It was built in an area facing Nanao Castle across the Masuda river, because it was the key point to control water for both farming and water transporting.

The 19th lord Fujikane moved their headquarters from Miyake Odoi to Nanao Castle as enmity between them and the Mori clan of Hiroshima developed.
The 20th lord Motoyoshi repaired Miyake Odoi when he remade it as their headquarters.

The buildings were protected with 5m tall earthen wall, and moat and river surrounded outside.
Inside the moat it was 190m from east to west, and 110m from north to south, which was far larger than other equivalent clan’s headquarters which normally fits within 100m square each.

Miyake Odoi along with Nanao Castle was designated as a National Historic Site.
Inside Miyake Odoi ground it is now marked where buildings and well stood.