Tenjin'yama Castle

Tenjin'yama Castle is a Japanese fortress in Nagatoro stretching roughly 300 meters along a narrow mountain ridge beside the Arakawa River. The structure uses the ridge's natural slope as part of its defense system, with a central watchtower area that commands views of the valley below.

The Fujita clan, originally from Yorii and descended from Kyoto nobles, established this fortress as their stronghold before submitting to the Hojo clan around 1550. This shift in allegiance represented a major change in regional power dynamics during the late medieval period.

The name reflects how Japanese fortresses were often named after mountain spirits or deities believed to inhabit the peaks. Visitors today can sense this connection to the landscape when standing on the ridge, where the natural setting feels inseparable from the human structures.

The fortress sits at a strategic location controlling the Chichibu-Oukan road between provinces and routes toward Kozuke province across Mase-Toge pass. Visitors should wear sturdy footwear and expect steep, uneven terrain, as the site follows the natural contours of the mountain ridge.

This structure ranks among the largest medieval fortifications in the Chichibu region, rising approximately 100 meters above the valley floor. Its prominent height made the fortress highly visible to travelers and merchants passing through the area, enhancing its role as a symbol of authority.