Location:  Owari Province.

Features:  Situated on a hill surrounded by plains.  The castle entrance was designed by connecting several barriers along an axis rather than enclosing one within the other, including moats and grass-covered mounds.  Some of the structures featured a traditional roof style made from dried miscanthus reed.

History:  Birthplace of Tokugawa Ieyasu in 1542.  Held by the Matsudaira clan.  Built in the Ryūtō hills surrounded by plains and at the convergence of the Sugō and Yahagi rivers.  Originally designated as the Ryūtōzan fort to defend against incursions from the north by the Nitsukishi clan of Mikawa Province.  Matsudaira Kiyoyasu captured the fort from Tsugiyori Nobusada, and following renovation and expansion, renamed it Okazaki castle.  In 1531, Kiyoyasu was killed in a rebellion known as the moriyama kuzure.  In 1549, Matsudaira Hirotada encountered a similar fate at the hands of rebels, after which the Imagawa took control of Okazaki.  In 1560, Matsudaira Motoyasu re-captured Okazaki following the surprise attack and death of Imagawa Yoshimoto at the battle of Okehazama.