Ryugajo

Ryugajo represents a fascinating intersection of Japanese military tradition and Western military science, built in 1867 as one of only two star-shaped forts constructed in Japan. This goryokaku, or five-pointed star fort, was constructed in Saku, Nagano, as a domain headquarters for the Matsudaira clan, who were affiliated with the powerful Sanada family. The adoption of Western fortress design principles reflected the dramatic technological and strategic shifts occurring in Japan during the final years of the Edo period.

The castle's five-pointed star configuration derives from European military engineering, which emphasized polygonal bastions capable of providing overlapping defensive fire. This design represented a fundamental departure from traditional Japanese castle architecture, which relied on curved walls, watchtowers, and concentric defensive rings. The construction of Ryugajo demonstrated how Japanese military planners were adapting to new weapons technologies, particularly artillery that rendered traditional castle designs vulnerable.

While smaller in scale than Hakodate's famous Goryokaku, Ryugajo retains its distinctive star-shaped earthwork fortifications and provides visitors with a tangible example of Japan's architectural transition during the 1860s. The site is listed among the Continued 100 Castles, a recognition of its historical and architectural significance. The fortress layout remains clearly visible, allowing visitors to understand how Western fortification principles were adapted to Japanese military needs.

Today, visitors can explore the earthwork fortifications and gain perspective on this unique period when Japan rapidly modernized its military infrastructure. The castle offers insight into the technological and cultural currents that shaped Japan's transition from feudal military systems to modern warfare during the Meiji Restoration era.

Ryugajo is recognized as one of Japan's second 100 castles as designated by the Japan Castle Foundation, a distinction that highlights its historical and architectural importance among the hundreds of castle sites across the country. As a Western-style star fort, its design reflects the defensive priorities and construction techniques of its era, with origins dating to 1867. Visitors traveling to Nagano Prefecture can explore the site alongside other regional historical attractions.