Uwajima Castle

Uwajima Castle is located in Maru-no-Uchi, Uwajima City, Ehime Prefecture, and was once an important fortress of Uwajima District in Iyo Province. Also known as Tsurushima Castle, it served as the administrative center of the Uwajima Domain during the Edo period. Today, the castle ruins are designated as a National Historic Site of Japan (1937), while the surviving tenshu (main keep) is recognized as an Important Cultural Property.

The origins of Uwajima Castle can be traced back to the medieval Itajima Marukushi Castle. Its layout as a modern castle was planned by the renowned warlord and master castle builder Todo Takatora. He constructed a hilltop castle (hirayamajiro) at an elevation of about 74 to 80 meters, adopting a terraced (teikaku-shiki) arrangement. At the summit stood the Honmaru (main bailey), around which were placed the Ninomaru, Taimaru (belt bailey), Tobemaru, Nagatomaru, Idomaru, and Sannomaru. Samurai residences were enclosed by an inner moat, creating a castle layout that combined both medieval and early modern characteristics. To the east, a water moat was connected to the sea, while the western side faced the ocean directly, making Uwajima Castle one of Japan’s rare “sea castles.”

One of its most celebrated features was the unique pentagonal outer enceinte. Whereas attackers usually anticipated square defensive layouts, the pentagonal structure created “dead angles” that served as blind spots against enemy assaults. These voided corners also functioned as secret entrances for counterattacks, supply routes, or even retreat passages. Such a design was highly unusual in contemporary castle-building techniques, showcasing Todo Takatora’s exceptional strategic ingenuity. It is said that hidden passageways once connected the castle interior to coastal boathouses and secret naval bases along the western shore, further demonstrating its military sophistication.

In later times, much of Uwajima Castle’s outer structures and seawater moats were filled in, erasing its former maritime castle appearance. After the Meiji period, most buildings were demolished, and following World War II the grounds were reorganized as Shiroyama Park. Although the Otemon (main gate) was destroyed in wartime air raids, the tenshu survived and remains designated as an Important Cultural Property. Other surviving features include the Noboritachi Gate (a municipal cultural property), stone walls, and the Yamazato Storehouse (now the Shiroyama Folk Museum). Unlike some other famous castles, Uwajima Castle currently has no plans for full wooden reconstruction; thus, the existing tenshu stands as the central remnant, offering visitors today a vivid glimpse into its history and architectural character.