Tonokori Castle (Miyazaki Prefecture): One of the Largest Medieval Mountain Castles in Western Japan, Conveying the Glory of the Ito Clan
Located in Saito City, Miyazaki Prefecture, Tonokori Castle is a mountain castle that flourished as the base of the Ito clan, who ruled Hyuga Province (present-day Miyazaki Prefecture) from the Nanboku-cho period to the Sengoku period. Boasting one of the largest scales in western Japan, measuring approximately 2 kilometers east-west and 1 kilometer north-south, it preserves the typical style of a medieval castle, surrounded by a moat and ponds totaling approximately 4 kilometers in length. Designated a national historic site on September 6, 2000, it is an important historical site indispensable to understanding the history of medieval castles in Japan.
History of Tonokori Castle: The 242 Years of Glory of the Ito Clan
Construction History and the Ito Clan’s Move to Hyuga
The history of Tonokori Castle dates back to the Nanboku-cho period, either in Kenmu 2 (1335) or Kenmu 4 (1337). It is said that the castle’s origins lie in the construction of a castle in Tono-gun, the site of the legendary Takayama Mausoleum, by Ito Sukemochi, who, at the command of Ashikaga Takauji, moved from Izu Province (present-day Shizuoka Prefecture) to Hyuga Province.
The Ito clan was originally a branch of the Kudo clan and a prestigious samurai family based in Ito-sho, Izu Province. During the turbulent Nanboku-cho period, they were entrusted with the governance of Hyuga Province by Ashikaga Takauji, which led to their relocation to the distant land of Kyushu. At this time, Ito Sukemochi chose a site for his castle on a plateau approximately 100 to 105 meters above sea level on the right bank of the Sanzai River, a tributary of the Hitotsuse River.
The Ito Clan’s Golden Age and Rule over Hyuga
The Ito clan, with Tono-gun Castle as their base, continued to rule the central part of Hyuga Province for 242 years. Especially during the Sengoku period (Warring States period), the Ito clan built a network of branch castles known as the “Forty-Eight Castles of Ito,” and reigned as a major power in Hyuga Province. Tono-gun Castle served as its center, becoming a political, military, and economic hub. Samurai residences, temples, shrines, and merchant districts were developed around the castle, creating a thriving castle town.
At its peak, the Ito clan’s influence extended to almost the entire Hyuga Province, controlling a vast area from the Miyazaki Plain to the Miyakonojo Basin. Tono-gun Castle functioned as both a symbol of their power and a de facto governing structure.
Conflict with the Shimazu Clan and the Fall of the Castle
The Ito clan’s glory came to an end with the Shimazu clan, the rulers of southern Kyushu. In 1577, the then-head of the Ito clan, Ito Yoshiyuki, suffered a defeat in battle against his arch-enemy, Shimazu Yoshihisa. The crushing defeat at the Battle of Kizakihara was particularly decisive, forcing Ito Yoshiyuki to abandon Hyuga Province and flee to Bungo Province (present-day Oita Prefecture) to seek refuge with Otomo Sorin.
This incident, known as the “Ito Collapse,” brought Tono-gori Castle under the control of the Shimazu clan. It was subsequently used as one of the Shimazu clan’s bases for controlling Hyuga, but it never regained the prosperity it had enjoyed under the Ito clan.
Abandonment and its Aftermath
In the Edo period, Tono-gori Castle was officially abandoned in 1615 (Keicho 20) due to the “One Castle Per Province” decree issued by the Edo shogunate. From then on, its function as a castle was completely lost, and over many years, the remains returned to nature. However, its magnificent scale and unique structure remain as a topographical feature, making it a valuable historical site that allows us to imagine its former glory even today.
Structure and Characteristics of Tono-gun Castle: A Large-Scale Castle Consisting of Five Enclosures
Arrangement of the Five Enclosures (Main Area)
The most distinctive feature of Tono-gun Castle is that it is composed of five main enclosures (kuruma), known as the “Five Enclosures.” Located at the northwestern edge of the Tono-gun Plateau, the main area consists of the following five enclosures:
Honmaru (Central Enclosure): This is the most important enclosure, forming the core of the castle. It is believed to have housed the lord’s residence and administrative offices. Situated on a plateau approximately 105 meters above sea level, it is protected by deep moats.
Ninokuruwa: This is the second most important enclosure after the Honmaru, serving to support it. It is presumed to have housed the residences of senior retainers and military facilities.
Sannomaru: This enclosure is located further out, strengthening defensive capabilities and likely serving as living space for many retainers.
Okunojo: Located behind (in the back of) the main keep, this enclosure served as the final defensive stronghold. It is also presumed to have functioned as an emergency evacuation site.
Nishinojo: Located on the west side, this enclosure was responsible for defending against enemies from the west.
These five enclosures formed an organically interconnected and complementary defensive system. Each enclosure was separated by moats and earthworks, designed to function as an independent defensive unit.
Defensive Network of Outposts
Several outposts were positioned around the main area consisting of the five enclosures. The following three outposts are particularly important:
Higashinojo: Located east of the main area, it functioned as a forward base against enemies from the east. It is also thought to have played a role in monitoring the opposite bank of the Sanzai River.
Mukainojo: Located on the south side, this outpost was an important base for blocking incursions from the south. It is located along the current National Route 325.
Nanjō (South Castle): This outpost was located south of Tōgōri Castle and, along with Mukōnojō Castle, was responsible for southern defense. Although it is now a plateau above fields, traces of the former castle grounds remain.
These outposts functioned as an outer defensive line protecting the main five castle fortifications, playing a role in detecting enemy approaches early and delaying attacks on the main castle.
Scale of the Outer Enclosure and Moat System
The most noteworthy feature of Tōgōri Castle is its magnificent “sōgamae” (outer enclosure). Sōgamae refers to a structure that surrounds not only the central part of the castle but also the entire castle town, including samurai residences, temples and shrines, and merchant districts, with defensive facilities.
The sōgamae of Tōgōri Castle extends over a vast area of approximately 2 kilometers east-west and 1 kilometer north-south, making it one of the largest in western Japan. This vast area was surrounded by moats and ponds stretching approximately 4 kilometers in total, and a defensive system that skillfully utilized the natural terrain was constructed.
The moats, fed by water from the Sanzai River, not only physically prevented enemy intrusion but also served as a water source for the castle. Furthermore, multiple ponds were strategically placed, each serving a dual purpose: defense and securing water for daily life.
Origin of the Alternate Name “Ukifune Castle”
Toogori Castle is also known by the beautiful alternative name “Ukifune Castle” (Floating Boat Castle). This name is said to originate from the fact that the castle, surrounded by vast moats and ponds, resembled a boat floating on the water.
Especially during the rainy season and floods, the moats would have been filled with water from the Sanzai River, making the castle grounds on the plateau appear literally like an island floating on water. This landscape enhanced the castle’s defensive capabilities while simultaneously symbolizing the authority and aesthetic sensibilities of the Ito clan.
The Current State of Tono-gori Castle: Designated as a National Historic Site
Historic Site Designation and Preservation Status
Tono-gori Castle ruins were designated as a National Historic Site on September 6, 2000. The designated area is Tono-gori, Aratake, Saito City, Miyazaki Prefecture, and the area centered around the five main castle enclosures is protected.
Currently, much of the castle site is farmland and forest, but the main remains are well preserved. In particular, the layout of the five castle enclosures—Honmaru, Ninomaru, Sannomaru, Okunojo, and Nishinojo—remains clearly visible as a topographical feature, allowing visitors to confirm the shapes of moats, earthworks, and enclosures.
Saito City is committed to the preservation and utilization of the historic site, and is promoting research, preservation, and environmental improvements for visitors. Information boards and explanatory signs have been installed to help visitors easily understand the history and structure of the castle.
Access and Visiting Information
Tono-gori Castle ruins are located approximately 5.9 kilometers southwest of Saito City’s urban area. The main part of the castle is located at the northwestern edge of the Tono-gun Plateau, which unfolds east of the point where the Sanzai River, originating from Mount Kunimi, flows northward.
Access by car is convenient; it takes about 40 minutes from Miyazaki City using National Route 219, etc. There is parking space around the castle ruins, from which you can explore the various remains on foot.
While visiting is generally free, some areas are private property, so caution is advised when entering. Also, due to the undulating terrain typical of mountain castles, comfortable shoes and clothing are recommended.
Highlights of the Ruins
The main highlights when visiting the site are as follows:
Layout of the Five Castle Enclosures: You can experience the layout of the five castle enclosures, centered around the main keep, by actually walking around. The moats and earthworks separating each enclosure demonstrate the advanced civil engineering technology of the time.
Moats and Earthworks: Deep moats separating the castle enclosures and earthworks built for defense remain in good condition. The deep moats around the main keep, in particular, demonstrate its high level of defensive capability.
View: Located on a plateau, it offers excellent views of the surrounding area. The flow of the Sanzai River, the city of Saito, and distant mountains can be seen, making it clear that this was a strategically important location for building a castle.
Positional Relationship of Outposts: By examining the locations of the surrounding outposts (Higashi-no-jo, Mukai-no-jo, Minami-jo, etc.) from the main keep, one can understand the overall defensive system of Tono-kori Castle.
Tono-kori Castle and the Forty-Eight Castles of Ito
Tono-kori Castle was the core castle of the “Forty-Eight Castles of Ito.” The Forty-Eight Castles of Ito is a collective term for the network of branch castles built by the Ito clan to control Hyuga Province; in reality, it is said that there were more than 48 castles.
These branch castles were arranged radially from Tono-kori Castle, forming a network that efficiently controlled and defended the entire territory. Each branch castle was staffed by members of the Ito clan or important retainers, who were responsible for governing and defending their respective regions. The main branch castles include Sadowara Castle, Takaoka Castle, Hokita Castle, and Nojiri Castle, all of which are important historical sites with surviving remains. When visiting Tono-gori Castle, visiting these surrounding branch castles as well will provide a deeper understanding of the Ito clan’s rule and the history of medieval Hyuga Province.
The Historical Context of Tono-gori Castle and Hyuga Province
To understand the history of Tono-gori Castle, it is important to know the historical context of Hyuga Province. Hyuga Province has been known as the “Land of Myths” since ancient times, and is a region with many mythological legends, including Takachiho, the site of the descent of the heavenly grandchild.
In the medieval period, Hyuga Province became an important strategic base in southern Kyushu. Located between the two major powers, the Otomo clan to the north and the Shimazu clan to the south, it was constantly in a state of tension. The Ito clan maintained their position as an independent force in this difficult situation through skillful diplomacy and military power.
The area around Saito City, where Tono-gori Castle is located, was the site of the Hyuga Provincial Government in ancient times and was historically one of the centers of Hyuga Province. It is believed that the Ito clan chose this location as their base because they recognized its historical and geographical importance.
The Value of Tono-gori Castle as a Medieval Castle
Tono-gori Castle occupies a very important position in the history of medieval castles in Japan. Its value can be summarized in the following points:
Grand Scale: The scale of its outer defenses, measuring 2 kilometers east-west and 1 kilometer north-south, is one of the largest in western Japan and among the largest medieval castles in the country.
Structural Complexity: The multi-layered defensive system, consisting of five castle enclosures and multiple outposts, is a prime example of the development of medieval mountain castles. It is also important that it was designed not merely as a military facility, but as part of a comprehensive urban plan including the castle town.
Utilization of Moats: The moat system, with a total length of 4 kilometers, is noteworthy as an advanced example of water use in medieval castles. The design, which skillfully utilizes the natural terrain and water system, demonstrates the advanced civil engineering technology of the time.
Excellent Preservation: Although more than 400 years have passed since the castle was abandoned, the main remains are in good condition, making it a valuable resource for studying the realities of medieval castles.
Historical Continuity: Having served as the base of the same clan (the Ito clan) for 242 years, it is a rare example that allows us to trace the development process of a castle throughout the medieval period.
Saito City and Tono-gori Castle: As a Regional Historical Heritage Site
Tono-gori Castle is one of Saito City’s representative historical heritage sites. Saito City also boasts the Saitobaru Kofun Cluster (a Special Historic Site), one of the largest groups of ancient burial mounds in Japan, making it a valuable region where one can experience the layered history from ancient to medieval times.
Saito City is focusing on tourism promotion and educational activities utilizing historical heritage, including the Tono-gori Castle ruins. The Saito City Tourism Association organizes guided tours and walks of the castle ruins, striving to help visitors gain a deeper understanding of the castle’s history and appeal.
Furthermore, local elementary and junior high schools provide opportunities to learn about the history of Tono-gori Castle as part of their local history education, fostering an understanding of and pride in the region’s history. Every year, local residents conduct cleaning and preservation activities, continuing efforts to protect and pass on the historical site throughout the community.
The Significance of Visiting Tono-gori Castle
Visiting Tono-gori Castle is more than simply seeing old castle ruins. It is an experience that allows you to feel firsthand the turbulent history of Japan from the Nanboku-cho period to the Sengoku period, particularly the rise and fall of Sengoku daimyo in Kyushu.
By actually walking through the vast outer fortifications, you can realize the grand scale of urban planning carried out by people in the Middle Ages. Witnessing the layout of the five castle enclosures and the depth of the moats allows you to understand the military technology and defensive thinking of the time.
Furthermore, the view of the Hyuga plain and sky from the plateau is likely not so different from the scenery seen by the heads of the Ito clan in the past. Within that view, one can contemplate the glory of the family that ruled this land for 242 years, and the tragedy of their eventual defeat and departure at the hands of the Shimazu clan.
Tono-gori Castle is an indispensable historical site when discussing the history of Miyazaki Prefecture, and a valuable legacy for understanding Japanese medieval history. When visiting Saito City, we highly recommend visiting the remains of this magnificent mountain castle and experiencing the depth of Hyuga’s history and culture.
Summary
Tono-gori Castle (Saito City, Miyazaki Prefecture) is one of the largest medieval mountain castles in western Japan, which flourished for 242 years as the base of the Ito clan, who ruled Hyuga Province from the Nanboku-cho period to the Sengoku period. With its magnificent outer fortifications measuring 2 kilometers east-west and 1 kilometer north-south, a complex defensive system consisting of five castle enclosures and multiple outposts, and a moat extending for a total of 4 kilometers, this valuable historical site, showcasing the development of medieval castles, was designated a national historic site in 2000.
The remains are still well-preserved, allowing visitors to experience the history of medieval Hyuga Province and the glory of the Ito clan while walking through the castle ruins. As a representative historical heritage of Miyazaki Prefecture and an important historical site for understanding the history of medieval Japanese castles, Tono-kori Castle will continue to convey the weight and charm of history to many people in the future.
