Oka Castle

Oka Castle (also known as “Gagyu Castle” or “Bungo-Takeda Castle”) is a classic mountain castle located in Taketa City, Ōita Prefecture. Built atop Mount Tenjin at an elevation of 325 meters, its stone walls stretch along the ridges in a dramatic fashion, often appearing to float above a sea of clouds. This has earned it the nickname “Castle in the Sky,” though it should not be confused with Hyōgo Prefecture’s Takeda Castle (famous under the same title), as the two castles are unrelated and even pronounced differently.

The origins of Oka Castle trace back to the Kamakura period. According to tradition, in 1185, Ogata Koreyoshi built the fortress to shelter Minamoto no Yoshitsune, who was being pursued by Minamoto no Yoritomo. During the Nanboku-chō period (1334), Shiga Sadatomo of the Ōtomo clan expanded the castle under the orders of Emperor Go-Daigo and named it “Oka Castle.” However, the historical record Bungo Kokushi suggests that the Shiga clan did not relocate here until 1369, having previously resided at Kimure Castle.

In the late Sengoku period, Oka Castle played a key defensive role due to its strategic terrain. In 1586, when the Shimazu clan invaded Bungo Province and devastated most of the Ōtomo domain, only Oka Castle, under the command of Shiga Chikatsugu, withstood repeated assaults. For his valor, Toyotomi Hideyoshi personally issued him a certificate of commendation.

After the fall of the Ōtomo clan, Shiga was forced out, and in 1594, Nakagawa Hidemasa from Harima Province was assigned to Oka Castle. He initiated a three-year reconstruction project, establishing the honmaru (main bailey), ninomaru, sannomaru, and numerous turrets on Mount Tenjin’s western slope, while also relocating the main gate. This shaped the layout of the castle ruins as seen today, with the surrounding Taketa castle town gradually developing thereafter.

During the Edo period, the Nakagawa clan governed the Oka Domain (also known as Taketa Domain), holding 70,000 koku of land. Although successive lords continued expansion and repairs, the castle was repeatedly damaged by natural disasters. A catastrophic fire in 1771 destroyed much of the honmaru, nishinomaru, and ceremonial halls, and later reconstructions were more modest.

Following the Meiji Restoration and the 1871 Abolition of Castles Order, all remaining buildings were dismantled by 1872, leaving only the towering stone walls that still convey its former grandeur. In 1936, the ruins were designated a National Historic Site. In 1990, Oka Castle Park was listed among Japan’s Top 100 Cherry Blossom Spots, and in 2006, it was officially included in the list of Japan’s Top 100 Castles (No. 95). Today, it remains a must-visit site for history enthusiasts and travelers alike.