Izushi Castle (Ariko-yama Castle)

Izushi Castle is an early-modern castle located in Izushi-cho, Toyooka City, Hyogo Prefecture. Together with the medieval mountain castle Ariko-yama Castle, which remains on the summit of Ariko-yama (elevation 321 m) behind it, it is a castle site that embodies the history of "Izushi, Tajima Province." The mountaintop Ariko-yama Castle ruins, together with the Konosumiyama Castle ruins, are designated as a National Historic Site under the name "Yamana Clan Castle Sites," while the Izushi Castle ruins at the foot of the mountain are designated as a historic site by Toyooka City. The castle town is called the "Little Kyoto of Tajima."

Izushi was the stronghold of the Yamana clan, who ruled Tajima from the medieval period. From the Nanboku-chō period through the Muromachi period, the Yamana clan was so powerful that they were called "Rokubun-no-ichi-dono" (lord of one-sixth of Japan), and there was a period when they controlled eleven of Japan's 66 provinces. Yamana Sōzen, who was also a principal cause of the Ōnin War (1467–77), embodied the peak of this clan. The Tajima Yamana clan ruled Tajima from Konosumiyama Castle and later from Ariko-yama Castle.

In the late Sengoku period, Hashiba Hidenaga, the younger brother of Hashiba Hideyoshi, invaded Tajima in Tenshō 8 (1580). Ariko-yama Castle fell, and the Yamana clan's rule of Tajima came to an end. After the Battle of Sekigahara, in Keichō 9 (1604), Koide Yoshihide built the early-modern Izushi Castle at the foot of the mountain as the center of political and administrative affairs. Ariko-yama Castle on the mountaintop was abandoned.

In the Edo period, a distinctive castle-town culture took shape. It included a clan internal dispute called the Sengoku Disturbance in the late Edo period, and the history of "Izushi sara-soba," said to have been brought by the Sengoku clan. The Sengoku clan was transferred from Ueda in Shinshu and brought soba culture with them. Today, the Izushi castle town still retains its Edo-period town layout. It is a tourist destination and, alongside Toyooka and Kinosaki Onsen, forms the core of Tajima's cultural tourism.