The ruins of a mountain castle designated as a National Historic Site, located in Taketa City, Oita Prefecture, and traditionally said to have been founded in 1185 (Bunji 1). The magnificent stone walls built atop sheer cliffs are celebrated as a breathtaking spectacle comparable to the "Japanese Machu Picchu," rivaling Takeda Castle in grandeur. The site is also famous as the place that inspired …

Oka Castle is traditionally said to have been founded in 1185 by Ogata Saburo Koreyoshi, who built it to welcome Minamoto no Yoshitsune. During the medieval period, the castle came under the control of the Otomo clan and served as a strategic stronghold in Bungo Province. In 1586, Shiga Chikanori su…