Koyama Castle

Koyama Castle is a fortified site in Yoshida, Japan, located on a rise near the Yuhigawa River. The site shows stone walls and three concentric water-filled ditches running around the central hill.

The castle arose in the second half of the 15th century as a border fortress in disputed territory. During the wars between the Takeda and Tokugawa, control over the site changed hands multiple times.

The name Koyama means small mountain, referring to the natural rise where the structure was built. Visitors today can walk through the former defensive layers, seeing how feudal lords used their position in the landscape.

The site now lies within Nomanji Mountain Park and is reachable on foot via maintained paths. A modern observation tower offers orientation over the grounds and a small museum displays finds from the Takeda period.

The site holds a rare system of three parallel water ditches, considered especially elaborate for the period. This defensive structure shows the high strategic value the place held during the years of conflict.

Location: Yoshida

GPS coordinates: 34.77894,138.24706

Latest update: December 5, 2025 22:30