Tsurumaru Castle (Miyagi Prefecture) Complete Guide: The History and Highlights of Kurihara City’s Mountain Castle, Dating Back to the Nanboku-cho Period
What is Tsurumaru Castle?
Tsurumaru Castle is a Sengoku period mountain castle located in Kurikoma Iwagazaki, Kurihara City, Miyagi Prefecture. It is said to have been built during the Nanboku-cho period by Tomizawa Kawachi-no-kami Dosuke, a member of the Kasai clan, and is situated on a hill approximately 101m above sea level on the left bank of the Sanpaku River.
It has several other names, including “Iwagazaki Castle,” “Tsurumaru-kan,” “Tsurumai Castle,” “Iwagazaki Fortress,” and “Iwagazaki-kan,” and has played an important role in the history of the region. Currently, it is maintained as Tateyama Park and is a popular cherry blossom viewing spot in spring.
History of Tsurumaru Castle
Construction During the Nanboku-cho Period
The history of Tsurumaru Castle dates back to the Nanboku-cho period. It is believed that the castle’s origins lie in the construction of a castle by Tomizawa Kawachi-no-kami Michisuke, a member of the Kasai clan, at this strategic location. As a senior retainer of the Kasai clan, the Tomizawa clan developed Tsurumaru Castle as their base of operations in the region.
At the time of its construction, the castle was a multi-bailey mountain castle measuring approximately 650m east-west and 400m north-south. The main bailey was located on the high ground north of the current Iwagazaki Elementary School, with four baileys—the second bailey, the third bailey, and the Ebisu-kan—connected to its east.
Changes in the Sengoku Period
During the Sengoku period, the lords of Tsurumaru Castle changed rapidly. After the Tomizawa clan, it came under the control of the Date clan, and subsequently, various clans related to the Date clan, such as the Ishimoda, Tamura, Furuchi, and Moniwa, served as castle lords.
Of particular note is the period when Date Masamune’s fifth son, Munetsuna, and sixth son, Munenobu, served as castle lords. This indicates that the Date clan considered this region important. After the pacification of Oshu in 1590, when the Date clan’s rule was established, Tsurumaru Castle functioned as an important base protecting the northern part of the Date territory.
The Edo Period and the Nakamura Clan
In the Edo period, the Nakamura clan became the lords of the castle in 1694, and they resided there until the Meiji Restoration. During the Nakamura clan’s rule, the castle maintained its function as a fortress while also developing as the center of territorial management.
As important retainers of the Sendai Domain, the Nakamura clan utilized Tsurumaru Castle as an administrative and military base in the region, and the town of Iwagazaki was also developed as a castle town. Throughout the Edo period, Tsurumaru Castle continued to function as the political and economic center of the Kurihara region.
After the Meiji Restoration
After the Meiji Restoration, Tsurumaru Castle was abolished due to the castle demolition decree, but the castle ruins were preserved as a local historical heritage site. Currently, the site is maintained as Tateyama Park and serves as a place of relaxation for citizens.
Structure and Layout of Tsurumaru Castle
Overall Structure
Tsurumaru Castle is a typical multi-bailey mountain castle, boasting a considerable size of approximately 650m east-west and 400m north-south. It features a layout that skillfully utilizes the hilly terrain, employing the Sanbaku River as a natural moat.
The main bailey (honkuruwa) is located at the highest point of the castle, with the second bailey, third bailey, and Ebisu-kan (Hiruko-kan) arranged in stages towards the east. This arrangement provided a defensive system that could prevent enemy incursions in stages.
Main Bailey (Honkuruwa)
The main bailey is the central part of the castle and is built at the highest elevation. It is believed that the lord’s residence and important facilities were located here. The remains of the earthworks are still clearly visible today, allowing us to imagine the scale of the castle at that time.
From the main enclosure, one could see the Kurihara Plain, indicating that it also functioned as a military observation post.
Second and Third Enclosures
The second and third enclosures, located east of the main enclosure, played a role in defending it. It is presumed that these enclosures housed the residences of retainers and barracks.
Moats were constructed between the enclosures to prevent enemy intrusion. Some remnants of these moats can still be seen today.
Ebisu Manor
Ebisu Manor was an enclosure located at the eastern end of the castle and was an important facility responsible for defending the castle from the east. The name of this manor is thought to originate from the Ebisu Shrine.
Defensive Structures
Tsurumaru Castle had various defensive structures. Remains such as earthworks, moats, well remains, and earthen bridges still exist today, demonstrating the high level of defensive technology of the time.
Particularly noteworthy are the ridged vertical moats. This is a defensive structure that made it difficult for enemies to move laterally by digging multiple parallel vertical trenches on a slope, and it is an important remains that demonstrates the characteristics of castle construction techniques from the Sengoku period.
Highlights of Tsurumaru Castle
Remains of the Enclosures (Kuruwa)
The greatest highlight of Tsurumaru Castle is the well-preserved remains of the enclosures. The layout of the main enclosure, second enclosure, and third enclosure can be clearly seen, making it an excellent learning tool for understanding the structure of mountain castles from the Sengoku period.
The flat surfaces of each enclosure remain clearly visible, allowing you to experience the scale of the time. The size of the main enclosure is particularly impressive, making it easy to imagine that the lord’s residence was located here.
Earthworks and Moats
The earthworks remaining in various places within the castle are important remains for understanding Tsurumaru Castle’s defensive system. In particular, the earthworks surrounding the main enclosure remain to a considerable height, allowing you to imagine its former appearance.
Moats separating the enclosures can also be seen in multiple locations, allowing you to learn about defensive techniques unique to mountain castles. These trenches not only prevented enemy intrusion but also served to control movement within the castle.
Ridge-shaped Vertical Moats
Among the defensive structures of Tsurumaru Castle, the ridge-shaped vertical moats are particularly noteworthy. These are remnants that demonstrate the characteristics of castle construction techniques from the late Sengoku period. By arranging multiple vertical moats parallel to each other on the slope, it was made difficult for the enemy to move laterally, thus hindering their approach to the castle.
Such clearly defined ridge-shaped vertical moat formations are rare even among mountain castles in Miyagi Prefecture, making them valuable remnants from the perspective of castle research.
Well Remains
Several well remains are preserved within the castle grounds. Securing water was one of the most important issues in mountain castles, and these wells were a lifeline during sieges. Traces of the wells can still be seen today, providing clues to imagining life in the castle at that time.
Earthen Bridges
Some earthen bridges, built to cross the trenches, also remain. The earthen bridge was an important facility for movement within the castle and also a strategically important defensive point. When the enemy attacked, destroying this bridge could prevent them from entering the castle.
Development as Tateyama Park
Currently, the Tsurumaru Castle ruins have been developed into Tateyama Park, a place of relaxation for citizens. Information boards and stone monuments explaining the castle’s history are installed within the park, allowing visitors to learn about the castle’s history while strolling around.
In spring, the cherry blossoms bloom profusely, making it a popular spot for cherry blossom viewing. The combination of the castle ruins and cherry blossoms creates a quintessentially Japanese atmosphere, attracting many tourists and local residents.
Access to Tsurumaru Castle
Access by Public Transportation
To access Tsurumaru Castle by public transportation, the nearest station is Kurikoma-Kogen Station on the JR Tohoku Shinkansen line. From the station, take a local bus and get off at the “Iwagazaki” bus stop, then it’s about a 10-minute walk to the castle ruins.
Since bus services are limited, we recommend checking the timetable in advance. Alternatively, if you take a taxi, it will take approximately 15 minutes from Kurikoma-Kogen Station.
Access by Car
If you are traveling by car, the nearest interchanges are Tsukidate IC or Wakayanagi-Kannari IC on the Tohoku Expressway. It takes approximately 20 minutes from either interchange.
Tateyama Park has a parking lot that is free to use. While there is ample parking space, it can get crowded during cherry blossom season, so visiting earlier in the day is recommended.
Address and Basic Information
- Address: Near 1 Shimo-koji, Kurikoma Iwagazaki, Kurihara City, Miyagi Prefecture
- Opening Hours: Always open (maintained as a park)
- Admission Fee: Free
- Parking: Available (free)
Nearby Tourist Attractions
Mount Kurikoma
Mount Kurikoma, located about 40 minutes by car from Tsurumaru Castle, is a famous peak spanning Miyagi, Iwate, and Akita prefectures. Especially during the autumn foliage season, a beautiful landscape known as “God’s Carpet” unfolds, attracting many hikers.
Izunuma and Uchinuma
Izunuma and Uchinuma, a Ramsar Convention registered wetland, are located about 30 minutes by car from Tsurumaru Castle. Tens of thousands of greater white-fronted geese migrate there in winter, making it a popular birdwatching spot.
Kurihara City Historical Museums
Kurihara City has several historical museums where you can learn about the history of the region, including Tsurumaru Castle. Visiting these museums in conjunction with a visit to the castle ruins will allow you to understand the history of Tsurumaru Castle more deeply.
Best Season to Visit
Spring (Late March to Early April)
Spring is the most popular season to visit Tsurumaru Castle ruins. The cherry blossoms planted in Tateyama Park are in full bloom, allowing you to enjoy the beautiful contrast between the castle ruins and the cherry blossoms. It is bustling with cherry blossom viewers, and you can also enjoy interacting with locals.
Early Summer (May to June)
The season of fresh greenery is also suitable for visiting. The weather is mild, making it ideal for strolling through the lush green castle ruins. There are relatively few tourists, allowing you to observe the remains at your leisure.
Autumn (October to November)
The autumn foliage season is also not to be missed. The surrounding mountains change color, and the view from the castle ruins becomes beautiful. The temperature is pleasant, making it a suitable season for strolling.
Winter (December to February)
During winter, snow can accumulate, creating a magical atmosphere when the castle ruins are covered in snow. However, the ground can become slippery, so caution is necessary when visiting.
Cultural Value of Tsurumaru Castle
Historical Value
Tsurumaru Castle functioned as a central castle in the region for approximately 500 years, from the Nanboku-cho period to the Meiji Restoration. The fact that various clans who shaped the history of the Tohoku region, such as the Kasai, Date, and Nakamura clans, served as castle lords throughout this long history demonstrates the castle’s historical importance.
In particular, the fact that the sons of Date Masamune became castle lords speaks to how much importance the Date clan placed on this region, making it an important historical site for understanding the political situation in the Tohoku region during the Sengoku period.
Archaeological Value
The remains of Tsurumaru Castle are valuable resources for understanding the structure of mountain castles from the Sengoku period to the Edo period. In particular, defensive structures such as the ridged trenches are important evidence of the level of castle construction technology at the time.
The remains of baileys, earthworks, and moats are well-preserved, and further detailed information about the castle’s structure may be revealed through archaeological excavations and surveys.
Regional Cultural Heritage
Tsurumaru Castle is an important cultural heritage site of Kurihara City and is central to the region’s identity. Having been developed as Tateyama Park, it has become an integral part of the lives of the citizens while preserving its value as a historical heritage site.
Local elementary schools utilize it as part of their local history curriculum, learning about the history of Tsurumaru Castle, and it also functions as a place for passing on history to future generations.
Tsurumaru Castle and Miyagi Prefecture’s Castle Culture
Comparison with Mountain Castles in Miyagi Prefecture
While many mountain castles exist in Miyagi Prefecture, Tsurumaru Castle is particularly noteworthy for its scale and state of preservation. Unlike large-scale early modern castles such as Sendai Castle (Aoba Castle), it is characterized by its strong resemblance to mountain castles of the Sengoku period.
While there are several other castle ruins in the Kurihara region, few examples retain their remains as clearly as Tsurumaru Castle, making it a central site in regional castle research.
Position in the History of Castles in the Tohoku Region
In the history of castles in the Tohoku region, Tsurumaru Castle embodies a major historical shift: the power shift from the Kasai clan to the Date clan, and the transition to the stable Edo period.
In particular, its role as a key point in the northern defense of the Date clan’s territory provides important clues to understanding the Date clan’s expansion and the realities of their rule.
Preservation and Utilization Efforts
Current State of Preservation
Tsurumaru Castle ruins are maintained as Tateyama Park, and therefore a certain level of preservation and management is in place. Many of the remains are in good condition, and the main baileys and earthworks, in particular, are clearly visible.
However, in some areas, the remains are difficult to see due to tree growth and natural weathering. Continued maintenance and management are future challenges.
Information Boards and Explanatory Facilities
Information boards explaining the history and structure of the castle are installed within the park, creating an environment where visitors can learn independently. A stone monument has also been erected, clearly indicating the historical significance of the castle ruins.
Further detailed explanations and the development of a more comprehensive information provision system, such as information provision utilizing smartphones, would further enhance its value as a tourist resource.
Collaboration with the Local Community
Kurihara City is working to promote tourism utilizing the local historical heritage, including the Tsurumaru Castle ruins. Through collaboration with local history enthusiasts and local history research groups, research and information dissemination about the castle’s history are being carried out.
In addition, the site is utilized in conjunction with local events during cherry blossom season, strengthening the connection between the historical heritage and the local community.
Points to Note When Visiting Tsurumaru Castle
Clothing and Equipment
Since Tsurumaru Castle is a mountain castle, comfortable walking shoes and clothing are recommended when visiting. Especially if you plan to carefully observe the remains, you may need to walk on slopes, so trekking shoes would be useful.
In summer, we recommend bringing insect repellent, a hat, and drinking water. In winter, be sure to take precautions against the cold and be aware of snow and ice.
Visitor Etiquette
Tsurumaru Castle Ruins is a valuable historical site and also a place of relaxation for local residents. Please observe basic manners, such as being careful not to damage the remains and always taking your trash with you.
Climbing on or digging in the remains such as earthworks and moats is strictly prohibited as it will lead to the destruction of the ruins.
Estimated Time Required
For a thorough visit to Tsurumaru Castle Ruins, allow approximately 1 to 1.5 hours to observe the remains. A light stroll through the park can be done in about 30 minutes.
Ideally, plan for around 2 hours, including time for photography and enjoying the surrounding scenery.
Summary
Tsurumaru Castle in Kurihara City, Miyagi Prefecture, is an important historical site that functioned as a central castle in the region for approximately 500 years, from the Nanboku-cho period to the Meiji Restoration. Built by Tomizawa Dosuke, a member of the Kasai clan, Tsurumaru Castle was later ruled by various prominent families who played a significant role in the history of the Tohoku region, including the Date and Nakamura clans.
This mountain castle, measuring approximately 650m east-west and 400m north-south, is a multi-bailey style castle centered around four baileys: the main bailey, the second bailey, the third bailey, and the Ebisu Manor. Defensive structures such as earthworks, moats, and ridged vertical trenches are strategically placed around these baileys. These remains are still well-preserved, making them valuable resources for understanding the structure of mountain castles from the Sengoku period.
Currently, the site is maintained as Tateyama Park and is a popular cherry blossom viewing spot in spring. Tsurumaru Castle’s greatest appeal lies in its combination of historical heritage value and function as a community gathering place.
With relatively easy access from Kurikoma-Kogen Station and ample parking, it’s a castle site easily accessible not only to history enthusiasts but also to general tourists. It’s a historical spot you should definitely visit when in Miyagi Prefecture.
By learning about the history of Tsurumaru Castle and exploring its remains, you can experience firsthand the history of the Tohoku region from the Sengoku period to the Edo period. This castle site, which has been carefully preserved by the local people, will continue to be passed down to future generations as a valuable cultural heritage of Kurihara City.
