As was the case with Toyotomi Hideyoshi’s Osaka Castle, the exterior walls of Okayama Castle’s Tenshu (castle tower) are covered with black clapboards, and because of the appearance, Okayama Castle also became known as “Ujo” (“U” means crows). Since gilded roof tiles from the era of Ukita Hideie have been excavated, it is presumed that during the construction of the castle, gilded roof tiles were used throughout the main buildings of the castle to present a dignified and powerful feudal lord under the Toyotomi regime. For this reason, the castle also became known as “Kin-ujo (golden crow castle).”

 Another feature of the castle is that a flat surface of the stone wall and the first floor of the Tenshu are in a scalene pentagonal shape, which is said to be due to the land shape of the hill of Okayama where the castle was built. In addition, a salt warehouse was attached to the west side of the Tenshu as a connecting turret, and there was an entrance to the Tenshu.

 The Tenshu was a precious architectural legacy that remained until after the Meiji Restoration and its detailed drawings were made in the early Showa era. However, the Tenshu was destroyed by fire during the Second World War. In 1966, the Tenshu was reconstructed as a reminder of the past.