Château de Toishi

Château de Toishi is a fortress site in Nagano Prefecture, Japan, set on a wooded hill above the Chikuma River. The ruins show stone walls and terraces spread across several levels, offering views over the valley below.

The fortress was built during the Sengoku period, when regional rulers raised hilltop defenses to protect their lands. Sanada Yukitaka captured the site after a long siege, which marked its role in the regional struggle for power.

The fortress took its name from the stony ground common in this part of Shinano, where builders shaped hillsides into defensive platforms. Visitors today can see the terraced layout that shows how defenders arranged their positions during conflicts.

Access is by a steep forest trail that requires sturdy footwear and can become slippery when wet. The walk takes around half an hour and passes through dense vegetation with some steep sections.

The siege stretched over a full year, which was unusually long for the time and showed the determination of both sides. Defenders used the steep slopes and narrow paths to inflict heavy losses on the attackers.