Kaseyama Castle: The Full Picture of Yamashiro Province’s Largest Medieval Castle and Matsunaga Hisahide’s Strategic Base
What is Kaseyama Castle?
Kaseyama Castle is a medieval mountain castle located in Kaseyama, Kizugawa City, Kyoto Prefecture (formerly Soraku District, Yamashiro Province). Built on a hill commonly known as “Shiroyama” (Castle Mountain) at an altitude of 136 meters (some sources say 141 meters), it boasts a vast castle area spanning 350 meters east-west and 300 meters north-south, and is known as one of the largest castles in the southern Yamashiro region.
The sheer size of this castle indicates that it was not merely a castle of a local lord, but one built by a powerful force of the daimyo class, ruling an entire province. Even today, the remains are well-preserved, making it an important historical site in the study of medieval castles.
History of Kaseyama Castle
Construction Date and Early Lords
The exact construction date of Kaseyama Castle is unknown, but the first documented mention dates back to Bunmei 11 (1479), with a record of a scholar from Kofuku-ji Temple entering the castle in the *Daijoin Jisha Zatsujiki* (Records of Miscellaneous Matters of Daijoin Temple). From this record, it is believed that the castle was initially under the control of Kofuku-ji Temple and managed by Kizu Shikko, a member of the Kofuku-ji monks.
Kofuku-ji Temple was a large temple based in Yamato Province (present-day Nara Prefecture), and its influence extended to the southern part of Yamashiro Province. It is presumed that Kaseyama Castle functioned as a military base for Kofuku-ji Temple to maintain its influence in Yamashiro Province.
Kaseyama Castle during the Kofuku-ji Period (First Period)
During the period when Kaseyama Castle was under the control of Kofuku-ji Temple, it was a strategic base controlling a key transportation hub in the Kizu River basin. Kizu has been a key point for land and water transportation since ancient times, situated at an important location connecting Nara and Kyoto.
While there are few clear records regarding the structure of the castle during this period, it is certain that a castle of a certain size existed to maintain the power of Kofuku-ji Temple. The existence of the position of Kizu Shikkou (Kizu Executive) also indicates the importance of this region.
Kaseyama Castle during the time of Matsunaga Danjo Hisahide (Second Reconstruction)
The most important turning point in the history of Kaseyama Castle is the renovation by Matsunaga Hisahide (Matsunaga Danjo), who ruled Yamato Province during the Sengoku period. In 1559, Matsunaga Hisahide invaded Yamato Province from his base at Shigisan Castle and eventually seized control of the entire province.
Hisahide extensively expanded and renovated Kaseyama Castle as a northern defense to protect his own bases, Tamon-yama Castle (Nara City) and Shigisan Castle (Ikoma District, Nara Prefecture). Most of the remaining structures are believed to date back to the renovations carried out by Matsunaga Hisahide.
Matsunaga Hisahide is known for his innovative castle-building techniques, and is credited with constructing Japan’s first multi-story turret (the prototype of the castle keep) at Tamon-yama Castle. His advanced castle-building philosophy is also reflected in Kaseyama Castle, where multiple baileys were arranged within the vast castle grounds, creating a robust defensive system.
The Castle’s End
After surrendering to Oda Nobunaga once, Matsunaga Hisahide rebelled again and committed suicide at Shigisan Castle in 1577. The detailed history of Kaseyama Castle after that is unknown, but it is believed that its role as a military base ended with Hisahide’s downfall.
Kaseyama Castle’s Layout and Remains
Overall Castle Structure
Kaseyama Castle has a distinctive layout in which the main baileys are arranged side-by-side from east to west. At the center of the castle are the main enclosures known as Enclosure 1, Enclosure 2, and Enclosure 3, with multiple smaller enclosures built in stages along the ridges extending southward from each enclosure.
This arrangement is thought to be a design that created a defensive system capable of responding to attacks from multiple directions, as well as a way to efficiently manage the vast castle grounds. It is a magnificent structure befitting the largest castle in the southern mountain castle district.
Main Path and Vertical Moats
Upon ascending from the main path, several vertical moats are clearly visible. Vertical moats are defensive structures dug vertically into the slopes, serving to prevent lateral movement of the enemy and limit attack routes. The vertical moats of Kaseyama Castle are well-preserved and are valuable remains for learning about the defensive techniques of medieval mountain castles.
Enclosure Groups
Numerous terraced enclosures are built on each ridge, and their number and scale are astonishing to visitors. Enclosures are flat, constructed areas used for troop garrisons, storage of supplies, and command posts. The baileys of Kaseyama Castle were designed to accommodate a large army, reflecting Matsunaga Hisahide’s strategic intentions.
Earthworks and Moats
Within the castle grounds, earthworks (defensive structures made of raised earth) and moats (ditches to prevent enemy intrusion) remain in excellent condition. These remains are thought to have been constructed during Matsunaga Hisahide’s renovations, demonstrating the high level of castle-building technology of the time.
Earthen Bridges
Earthen bridges crossing the moats can also be seen. These bridges were structures created by leaving sections of the moat unexcavated to serve as pathways, limiting entry and exit points to the castle and strengthening its defenses.
About Visiting Kaseyama Castle
Access Methods
Using Public Transportation:
- Approximately 15 minutes on foot from Kizu Station on the JR Nara Line, Yamatoji Line, and Gakken Toshi Line.
- Kizu Station is a convenient station with multiple lines, providing good access from both Kyoto and Nara.
Using a Car:
- Please check in advance regarding the availability and location of parking.
- As the surrounding area is residential, street parking should be avoided.
Points to Note During Your Visit
Estimated Time Required:
A typical visit takes approximately 1 hour and 15 minutes, but more time is needed for detailed observation of the remains.
Preparation for Your Visit:
- As it is a mountain castle, comfortable clothing and walking shoes are essential.
- Insect repellent may be necessary depending on the season.
- Bringing drinking water is recommended.
Using the Site Map:
A site map of the castle is available in a box located below the information board at the site. Bringing this map will deepen your understanding of your current location and the remains.
Points to Note During Your Visit
- The remains are valuable cultural assets. Please be careful not to damage them while viewing them.
- Some parts of the mountain path are slippery, so please watch your step.
- It is recommended to avoid visiting on days with bad weather.
- Please be sure to take your trash with you.
Cultural Value of Kaseyama Castle
The Largest Scale in Minami-Yamashiro
Kaseyama Castle, with its vast castle grounds and well-preserved remains, is an important resource for the study of medieval castles in the Minami-Yamashiro region. Its scale of 350 meters east-west and 300 meters north-south far surpasses that of local lords’ castles and is comparable to that of daimyo-class castles.
Matsunaga Hisahide’s Castle Construction Techniques
The existing remains reflect the castle construction philosophy of Matsunaga Hisahide, one of the representative warlords of the Sengoku period. Hisahide realized innovative castle architecture at Tamon-yama Castle, and this pioneering spirit can also be seen at Kaseyama Castle. The effective arrangement of multiple baileys and the defensive system utilizing vertical moats and earthworks demonstrate the most advanced castle-building technology of the time.
Importance in Local History
Kaseyama Castle is an important historical site that shows the shift in power structure from the medieval period to the Sengoku period, from the sphere of influence of Kofuku-ji Temple to the rule of Matsunaga Hisahide. Its location in the Kizu River basin, a crucial transportation hub, also speaks to the strategic importance of this region.
Surrounding Historical Environment
History of Kizu
Kizu has flourished since ancient times as a key point for land and water transportation. The Kizu River is an important river in the Yodo River system and a major artery for transporting goods between Nara and Kyoto. It also functioned as an outer port for Heijo-kyo (the ancient capital), and has developed as a historically important region.
Relationship with Kofuku-ji Temple
Kofuku-ji Temple is a large temple that has existed since the Nara period and reigned as the de facto ruler of Yamato Province during the medieval period. His influence extended to the southern part of Yamashiro Province, and Kaseyama Castle was an important base located at the northern edge of his sphere of influence.
Matsunaga Hisahide’s Base Network
Matsunaga Hisahide used Tamon-yama Castle as his base and controlled Yamato Province and its surrounding areas from bases such as Shigi-san Castle and Kaseyama Castle. These castles formed a mutually interconnected defensive network, and Kaseyama Castle played a crucial role in defending the north.
Significance of Visiting Kaseyama Castle
For History Enthusiasts
Kaseyama Castle is not a castle widely known throughout Japan, but those who actually visit will be surprised by the excellent state of preservation of the remains and the vastness of the castle grounds. Few castles are more suitable for understanding the structure of medieval mountain castles.
From the Perspective of Castle Research
As the largest castle in southern Yamashiro Province, and as a site demonstrating Matsunaga Hisahide’s castle-building techniques, it holds high academic value. There are many points to observe, including the tiered arrangement of baileys on each ridge, the clearly preserved vertical moats, and the layout of earthworks and moats.
As a Regional Cultural Asset
For Kizugawa City, Kaseyama Castle is an important cultural asset and a valuable historical site that tells the story of the region’s history. In recent years, improvements have been made to accommodate visitors, such as the installation of explanatory signs and layout maps.
Events and Utilization
Kizugawa City sometimes holds events utilizing regional cultural assets, including Kaseyama Castle. History lectures and guided tours are sometimes planned, so those interested are advised to check Kizugawa City’s official information.
By supporting Kizugawa City through hometown tax donations, you can also support the preservation and utilization of these cultural assets.
Summary
Kaseyama Castle is an important historical site, boasting the largest scale of a medieval mountain castle in the Minami-Yamashiro region, with a history of succession from Kofuku-ji Temple to Matsunaga Hisahide. Built on a 136-meter-high hill, the vast castle grounds of Kaseyama Castle retain remarkably well-preserved remains such as baileys, vertical moats, earthworks, and trenches, making it a valuable resource for studying the structure of medieval castles.
Thanks to the large-scale expansion and renovation by Matsunaga Hisahide, Kaseyama Castle played a strategic role as a northern defense, and as a relic demonstrating the most advanced castle construction technology of the time, it holds high value in castle research.
With its easy accessibility—approximately a 15-minute walk from JR Kizu Station—it is a historical site well worth visiting for history buffs and castle enthusiasts. Visiting the site and witnessing the magnificent remains firsthand allows for a deeper understanding of the history from the medieval period to the Sengoku period.
Kaseyama Castle, which is being preserved and utilized as a cultural property, is an important historical site that is expected to become even more widely known and visited in the future.
