Matsushiro Castle is a historic castle site in Matsushiro, Nagano City, Nagano Prefecture. Originally known as Kaizu Castle, it is closely associated with the famous Battles of Kawanakajima between Takeda Shingen and Uesugi Kenshin during Japan’s turbulent Sengoku period.
The castle was also known by names such as Kaizu Castle and Kayatsu Castle. The name Kaizu is traditionally said to have been connected with the abundant growth of reeds and other grasses in the area.
From its origins as a strategic military stronghold to its later role as the administrative center of the Matsushiro Domain under the Sanada family, the castle underwent many changes throughout Japanese history. Today, the site is preserved as a National Historic Site and offers visitors an opportunity to explore the history of the region.
The exact date when Kaizu Castle was first constructed remains uncertain, but construction is traditionally believed to have begun in 1559 and been completed the following year.
When Takeda Shingen confronted Uesugi Kenshin in the Kawanakajima region, the castle’s position along the Chikuma River made it an important military base. It was developed as a strategic stronghold from which the Takeda forces could operate in northern Shinano.
According to the historical chronicle Kōyō Gunkan, Shingen took control of the residence of the influential local Kiyono clan and ordered the construction of the castle. The project is traditionally associated with Yamamoto Kansuke, a military strategist known for serving Shingen.
Local powerful families, including the Yashiro and Kōsaka clans, are also said to have assisted with the construction. Leaders from the four districts of northern Shinano—Sarashina, Hanishina, Takai, and Minochi—were reportedly involved as well.
Kaizu Castle played a particularly important role during the Fourth Battle of Kawanakajima in 1561, one of the most famous conflicts of Japan’s Sengoku period.
The Takeda commander Kasuga Toratsuna, also known as Kōsaka Masanobu, held the castle and prepared to face Uesugi forces. The confrontation eventually developed into the fierce battle at Hachimanbara.
Because of its strategic position, Kaizu Castle was important not only during the battles themselves but also as a base for controlling northern Shinano.
In 1582, the Takeda clan was destroyed, and the area came under the control of Mori Nagayoshi, a retainer of Oda Nobunaga.
Mori is said to have taken members of local families and the children of former Takeda retainers as hostages and had them live in or around Kaizu Castle.
Later that same year, the Honnō-ji Incident dramatically changed the political situation in Japan. Following the death of Oda Nobunaga, Mori Nagayoshi withdrew from Shinano, temporarily leaving Kaizu Castle without a lord.
The castle subsequently came under the control of Uesugi Kagekatsu. In 1585, Suda Mitsuchika was appointed as castle commander.
When Uesugi Kagekatsu was transferred to Aizu in 1598, Tamaru Naomasa became lord of Kaizu Castle, which was administered as territory under the direct control of Toyotomi Hideyoshi.
The castle’s defensive design during this period reflected features associated with Kōshū-style castle construction, including structures such as maru umadashi defensive enclosures and crescent-shaped moats. These features reveal how the castle evolved in response to the military techniques of the Sengoku period.
In 1600, Mori Tadamasa replaced Tamaru Naomasa as lord of the domain. Around this time, Kaizu Castle was renamed Machishiro Castle.
The castle subsequently passed through the hands of several feudal lords, including Matsudaira Tadateru, Matsudaira Tadanao, and Sakai Tadakatsu.
In 1622, Sanada Nobuyuki entered Matsushiro, beginning the long association between the castle and the Sanada family. From then on, the Sanada clan governed the Matsushiro Domain for generations.
Under the Sanada family, Matsushiro Castle became the administrative center of the Matsushiro Domain. It served as the political heart of the domain and played an important role in governing the surrounding region.
At the same time, commercial activity was concentrated around the pilgrimage town of Zenkoji. As a result, Matsushiro developed primarily as a political and administrative town rather than as a major commercial center.
Matsushiro Castle experienced several major disasters throughout the Edo period. In 1717, a fire destroyed the main enclosure as well as the second and third baileys. The castle was rebuilt the following year with financial assistance from the shogunate.
The castle and surrounding town were later affected by the 1742 Great Flood and the 1847 Zenkoji Earthquake. Each time, reconstruction and restoration efforts helped the castle and town recover.
In the final years of the Edo period, the Sanada family constructed a residence known as the Shin-Goten, or Sanada Residence. It served as the family’s residence and continued to symbolize the political authority of the Matsushiro Domain during the final years of feudal rule.
Following the Meiji Restoration and the abolition of the feudal domain system, Matsushiro Castle was officially abandoned in 1872. The former castle grounds were subsequently sold or transferred to former samurai families and others, and parts of the site were converted into farmland and residential land.
In 1873, the Hanenomaru Palace was destroyed by another fire. Over time, most of the original castle buildings disappeared.
In 1879, a stone monument commemorating the former Hanenomaru site was erected. Although the physical castle had largely disappeared, efforts to preserve its historical memory continued into the modern era.
Today, the Matsushiro Castle ruins have been developed as a historic park. Sections of the castle, including turret foundations, moats, and stone walls, have been reconstructed to help visitors understand the appearance and defensive structure of the former stronghold.
The site is particularly beautiful in spring, when cherry blossoms add color to the historic landscape. The peaceful surroundings make the castle ruins a pleasant place for a walk while learning about the region’s past.
The area surrounding Matsushiro Castle is also home to several important historical attractions, including the Sanada Treasure Museum and the Sanada Residence. Together, these sites make Matsushiro an excellent destination for exploring the history of the Sanada family and the former Matsushiro Domain.
Matsushiro Castle reflects several major chapters of Japanese history. It began as Kaizu Castle, a strategic military stronghold during the Sengoku period, and later became the political center of the Matsushiro Domain under the Sanada family during the Edo period.
Over the centuries, the castle was connected with powerful figures and ruling families including the Takeda, Uesugi, Toyotomi, Tokugawa, and Sanada. Its history therefore extends far beyond that of a single castle, revealing the changing political and military landscape of central Japan.
Today, the preserved castle ruins offer visitors a chance to walk through this layered history. With its reconstructed stone walls, moats, seasonal scenery, and nearby historic buildings, Matsushiro Castle is one of Nagano’s most rewarding destinations for travelers interested in Japan’s samurai heritage.