The History of a Sengoku-Era Stronghold
Minowa Castle is traditionally believed to have been built in 1512 by Nagano Narinao. It subsequently became the main stronghold of the Nagano clan and reached its height during the rule of Nagano Narimasa.
Narimasa is remembered as a powerful warlord who allied himself with the Uesugi clan of Echigo and repeatedly resisted invasions by Takeda Shingen. With its strong defensive position, Minowa Castle developed a reputation as an exceptionally difficult fortress to capture and became an important base in the province of Kozuke, corresponding roughly to present-day Gunma.
In 1566, however, the Takeda army launched a major assault and finally captured the castle. The young lord Nagano Narimori met a tragic end, bringing the Nagano clan’s rule to an end.
Afterward, the castle became a Takeda stronghold. Figures including Amari Masatada, Sanada Yukitaka, and Naitō Masatoyo served as commanders of the castle.
Following the destruction of the Takeda clan in 1582, Minowa Castle passed under the control of the Oda clan and later the Hōjō clan. After Toyotomi Hideyoshi’s campaign against the Hōjō in 1590, Ii Naomasa, a retainer of Tokugawa Ieyasu, entered the castle.
Naomasa expanded and remodeled Minowa Castle as a more developed early-modern fortress. However, in 1598, he moved his base to the newly developed Takasaki Castle. Minowa Castle was subsequently abandoned, bringing approximately 80 years of castle history to an end.
The Castle Layout and Highlights
Minowa Castle was a hirayamajiro, or fortified hill castle, built in a tiered layout on a river terrace formed by the Haruna-Shirakawa River. The river protected the western side, while Lake Haruna-numa to the south provided another natural defensive feature.
The castle occupied an enormous area measuring approximately 500 meters from east to west and 1,100 meters from north to south, covering roughly 47 hectares.
Sannomaru Stone Walls
Among the most impressive surviving features are the Sannomaru stone walls. Reaching approximately 4.1 meters in height, these walls demonstrate advanced castle-building techniques from a period when Japanese fortifications were evolving from Sengoku-era strongholds into more substantial early-modern castles.
The stonework provides an important example of the transition in Japanese castle construction during this period.
Kuruwa Umadashi West Entrance Gate
In 2016, the Kuruwa Umadashi West Entrance Gate was reconstructed in wood based on historical research.
The gate forms part of the castle’s defensive system and helps visitors visualize how access to the fortress was controlled. Plans have also included the possible reconstruction of the western entrance gate of the main enclosure, which would make the original layout easier to understand.
Walking Through History and Nature
Today, the Minowa Castle ruins feature five walking routes. Each season offers a different atmosphere: cherry blossoms and fresh greenery in spring, lush vegetation in summer, colorful foliage in autumn, and clear air and open views in winter.
Many of the castle’s earthen ramparts and dry moats remain relatively well preserved. Walking along these features provides a much better sense of the scale and defensive structure of the original castle than viewing the site from a single location.
The surrounding area also retains place names associated with the former castle town. Names such as Nishi-Akaya, Higashi-Akaya, Honcho, Renjaku-machi, and Kōya-machi preserve traces of the historic town layout and neighborhoods once associated with craftsmen and merchants.
Information signs explaining the origins of these place names can be found around the area, making them an interesting addition to a historical walking tour.
Minowa Castle Festival
The Minowa Castle Festival is held annually on the last Sunday of October.
During the event, local participants dress in samurai armor and take part in performances recreating the conflict between the Nagano and Takeda forces. The dramatic scenes provide visitors with an entertaining way to learn about the region’s Sengoku-period history.
The festival also serves as a local event for passing the history and cultural heritage of Minowa Castle on to future generations.
Access
The Minowa Castle ruins are located in Nishi-Akaya and Higashi-Akaya, Misato-machi, Takasaki, Gunma Prefecture.
From Takasaki Station, visitors can take a Gunma Bus service bound for Misato or Ikaho Onsen and get off at either Shiroyama Iriguchi or Higashi-Akaya. The castle ruins are approximately a five-minute walk from these stops.
Bus services are also available from Maebashi and Shibukawa. When planning a visit, check the route carefully, as services using the Hamagawa or Oki routes may be convenient depending on your departure point.
Experience the Romance of a Sengoku Castle
Minowa Castle offers a fascinating combination of Japanese history, castle architecture, and seasonal nature. Although the original buildings are gone, the surviving earthworks, moats, stone walls, gates, and enormous scale allow visitors to imagine the fortress that once stood here.
For history enthusiasts, the site offers an opportunity to trace the struggles of the Nagano, Takeda, Hōjō, and Tokugawa forces. At the same time, its walking paths and natural surroundings make it an enjoyable destination for visitors simply looking for a peaceful outdoor experience.
When traveling through Gunma, take time to explore the Minowa Castle ruins and discover the traces of the Sengoku period that remain hidden in the landscape.