Tsuwano Castle

Tsuwano Castle (Tsuwano-jō) stands atop Mount Reigisan in Kanoashi District of the former Iwami Province (present-day Tsuwano Town, Kanoashi District, Shimane Prefecture). It is a mountain castle built to take advantage of the steep terrain, and is also known as Sanbonmatsu Castle or Fuki Castle. Today, the ruins are designated a National Historic Site, with impressive stone walls and castle remains still preserved.

Mount Reigisan rises about 367 meters above sea level, commanding a view of the entire Tsuwano Basin and offering natural defensive advantages. The exact date of the castle’s construction is unknown, but it was already referred to as Sanbonmatsu Castle by the late Muromachi period (Sengoku era). To the south, along the mountain ridge, lies a branch fortification called Nakaara Castle, which is included within the historic site designation alongside Tsuwano Castle.

In the Edo period, Tsuwano Castle became the residence of the Kamei clan, rulers of the Tsuwano Domain. However, due to the steep mountain terrain, which was ill-suited for administrative functions, the Kamei placed their domain headquarters at the mountain’s base instead. Following the Meiji Restoration and the issuance of the Castle Abolition Order, Tsuwano Castle was officially abandoned.

Even today, visitors who climb to the summit can see well-preserved stone walls, as well as remains of moats, cuttings, vertical trenches, and continuous trench systems characteristic of mountain fortresses. At the foot of the mountain remain the Babasaki Yagura (a Shimane Prefectural Cultural Property) and the Watchtower. The former residence of the domain lords now serves as Shimane Prefectural Tsuwano High School, while its gardens have been maintained as Karakuen.

In addition, the castle ruins area has been incorporated into the Chūgoku Nature Trail. The hiking route from Washibara Hachiman Shrine to Taikodani Inari Shrine passes through the castle grounds, allowing visitors to experience the fusion of historical remains with the natural landscape.