Nyoigatake Castle: A strategically important mountain castle in Kyoto that oversaw the Onin War and the Sengoku period
Nyoigatake Castle is a medieval mountain castle built on the summit of Mt. Daimonji (elevation 465.8m) in Sakyo Ward, Kyoto City. It’s surprisingly little known that Mt. Daimonji, famous for the Gozan Okuribi (five mountain bonfires), was actually an important military base that served as the site of numerous battles from the Muromachi period to the Sengoku period.
This article provides a comprehensive explanation of this historical mountain castle, from its historical background and castle structure to existing remains and access methods.
Historical Background of Nyoigatake Castle
Construction History and the Onin War
The construction period of Nyoigatake Castle is believed to be around Bunmei 1 (1469). It is said that this castle was built around three years after the start of the Ōnin War by Taga Takatada, a powerful warlord from Ōmi Province who belonged to the Eastern Army.
The Ōnin War continued until 1477 (Bunmei 9), and during this time, Mount Nyoigatake became a strategically important base for the Eastern Army, controlling the “Nyoigoe” route, the shortest route connecting Kyoto and Ōmi. Descriptions of Taga Takatada deploying his forces on Mount Nyoigatake can be found in historical documents such as the *Daijōin Jisha Zatsuji Ki*.
The Fierce Battle of 1509 (Eishō 6)
The most important battle in which Nyoigatake Castle clearly appears in historical records took place in 1509 (Eishō 6). In that year, Hosokawa Sumimoto and Miyoshi Yukinaga, who had retreated to Ōmi Province due to a dispute over the succession of the Hosokawa clan, led their troops and deployed them on Mount Nyoigatake.
In response, a combined force of Hosokawa Takakuni, the Hatakeyama clan, and Ouchi Yoshioki launched a large-scale attack. After fierce fighting, Hosokawa Sumimoto and Miyoshi Yukinaga were defeated and fled to Awa Province. This battle, known as the “Battle of Nyoigatake,” marked a crucial turning point in the internal conflicts of the Hosokawa clan.
Hosokawa Takakuni’s Deployment in Eisho 17 (1520)
Records show that in Eisho 17 (1520), Hosokawa Takakuni himself deployed his forces at Nyoigatake Castle. During this period, Hosokawa Takakuni held significant political power in Kyoto as Kanrei (deputy shogun), but the political situation remained unstable, indicating that Nyoigatake Castle functioned as a key point in Kyoto’s defense.
Ashikaga Yoshiteru and the Eve of the Eiroku Incident
With the arrival of the Sengoku period (Warring States period), Nyoigatake Castle became an important base also used by the Shogun’s family. In 1558 (Eiroku 1), Ashikaga Yoshiteru, the 13th Shogun of the Muromachi Shogunate, deployed his forces at Nyoigatake Castle and clashed with the army of Miyoshi Nagayoshi at Kitashirakawa.
At this time, the Shogun’s authority had significantly declined, and Ashikaga Yoshiteru’s conflict with the Miyoshi clan deepened. Deploying his forces from Nyoigatake Castle was a strategic decision to control the route of advance towards Kyoto, but ultimately Yoshiteru was forced to make peace with the Miyoshi clan.
Connection to the Hogen Rebellion
Going back to an even earlier period, there are accounts in texts such as the “Hogen Monogatari” (Tale of Hogen) that Emperor Sutoku entered Mount Nyoi during the Hogen Rebellion of 1156 (Hogen 1). While this event predates the construction of Nyoigatake Castle, it indicates that this area was recognized as a strategically important location from ancient times.
Location and Strategic Importance of Nyoigatake Castle
Nyoigatake Pass and the Kyoto-Omi Route
Nyoigatake Castle was built on Mount Daimonji, located in the central part of the Higashiyama mountain range, offering an excellent vantage point overlooking the Kyoto Basin. The “Nyoigatake Pass,” which passed along the southern foot of this mountain, was one of the shortest routes connecting Kyoto and Otsu (Omi).
The Nyoigatake Pass is an ancient road that runs from the present-day Shirakawa-dori, through Nyoi-ji Temple, to the Yamashina Basin. Used since the Heian period, this route was shorter than the Tokaido and Nakasendo roads and was used for the urgent movement of messengers and troops.
A Key Point for Kyoto’s Defense
From Nyoigatake Castle, one can overlook the Kyoto Basin, seeing Ginkaku-ji Temple, Yoshida-yama, the Kyoto Imperial Palace, and even the Nishiyama Mountains. This excellent view was militarily extremely important.
The routes for advancing from the Omi region to Kyoto were limited, with the main routes being the Nyoigatake Pass, the Yamanaka Pass (Sanjo Road), and the Osaka Barrier. Nyoigatake Castle had complete control over the Nyoigatake Pass and was also positioned to monitor movements on the other routes.
Relationship with Nyoi-ji Temple
To the south of Nyoigatake Castle, the remains of Nyoi-ji Temple are scattered over a wide area. Nyoi-ji Temple was an ancient temple founded during the Heian period, and at its peak, it possessed many buildings.
In the medieval period, temples were not merely religious facilities but sometimes functioned as military bases. The existence of Nyoi-ji Temple suggests the possibility that it was used as a rear support facility or supply base for Nyoigatake Castle.
The Castle Structure of Nyoigatake Castle
Overall Structure and Layout
Nyoigatake Castle is a large mountain castle extending approximately 1 km from east to west, centered on the summit of Mt. Daimonji (elevation 465.8 m). The castle is composed of three main sections.
Main Enclosure (Honmaru): Located at the summit, this is the most important core section. A fire pit (the fire pit for the Daimonji bonfire) still remains here, and it is believed to have been built on leveled land from the castle era.
Second Enclosure: Located southeast of the main enclosure, this enclosure serves a defensive function that complements the main enclosure.
Third Enclosure: Located northeast of the main enclosure, this enclosure played a role in preparing for attacks from the northeast.
These enclosures are clearly demarcated by dry moats, earthworks, and steep slopes, forming a coordinated defensive system.
Features of the Moat and Earthworks
The most distinctive feature of Nyoigatake Castle is the large-scale moat and earthworks surrounding the mountaintop. This moat extends east and west along the ridge, centered on the main enclosure, forming a powerful defensive line to prevent enemy intrusion.
The moat is approximately 3-5 meters wide and 2-3 meters deep, and is still clearly visible today. The earthworks were built inside the moat (on the castle side), and approximately 1-2 meters high remain.
This combination of moat and earthworks demonstrates castle construction techniques from the first half of the 16th century, and it is highly likely that a large-scale renovation was carried out during the battle of Eisho 6 (1509).
Ridge Blocking by Moats
Nyoigatake Castle features multiple moats along the east-west ridges. These moats are dry moats that cut perpendicularly across the ridge, serving to prevent enemy advances along the ridge.
The eastern moat, in particular, is large in scale, reaching depths of 4-5 meters in some places. These moats clearly defined the boundaries of the castle grounds and functioned as the front line of defense.
Lower Enclosures and Cut Slopes
Several lower enclosures (koshikuruwa) are positioned on the slopes leading from the main enclosure to the second and third enclosures. These lower enclosures are small, flat areas created by leveling the mountain slopes, and were used for troop deployment and supply storage.
Cut slopes (kirigishi) are artificially carved steep slopes that made it difficult for enemies to climb. The cut slopes of Nyoigatake Castle still maintain a height of 5-10 meters in some places, demonstrating the advanced civil engineering techniques of the time.
Structure of the Entrances (Koguchi)
Entrances to the main enclosure (koguchi) have been identified on the southwest and northeast sides. These entrances are not simple openings, but rather “staggered entrances” with curved earthworks that complicate the entry route.
This structure prevents the enemy from entering in a straight line, allowing the defenders to attack from the flanks.
Existing Remains and Points of Interest
Well-Preserved Earthworks and Moats
The greatest highlight of Nyoigatake Castle is the moat and earthworks surrounding the mountaintop. Despite being over 500 years old, these remains are remarkably well-preserved.
In particular, the moat extending from the west to the south of the main enclosure remains almost completely intact, making it a valuable relic that allows one to directly experience the castle construction techniques of the Sengoku period. Because it is located slightly off the hiking trail, careful observation is necessary.
Senjinzuka (Thousand-Person Mound)
Along the hiking trail to Daimonji Mountain, there is a stone monument called “Senjinzuka” (Thousand-Person Mound). This is a monument erected by local people as a memorial to the numerous human remains unearthed during the Pacific War by the army while digging air raid shelters (octopus traps).
These human remains are believed to belong to soldiers who died in the battle of 1509 and subsequent battles. The Senjinzuka (Thousand-Man Mound) is an important historical site that conveys the fierce battles that took place at Nyoigatake Castle.
Relationship between the Daimonji Fire Pits and Castle Remains
On the mountaintop, there are 75 fire pits used for the Daimonji bonfire festival. These fire pits were constructed after the Edo period, but their arrangement is thought to utilize the leveled ground of the main enclosure of Nyoigatake Castle.
Careful observation of the area around the fire pits reveals artificially leveled surfaces and traces of earthworks. This reveals an interesting layer of history where the traditional Kyoto event of the Daimonji bonfire festival overlaps with the remains of a castle from the Sengoku period.
View of the Kyoto Basin
From the mountaintop, you can enjoy a panoramic view of the entire Kyoto Basin. On a clear day, you can see as far as the Kyoto Imperial Palace, the five-story pagoda of Toji Temple, Mount Hiei, and Mount Atago, giving you a real sense of the castle’s strategically important location.
The view to the southwest is particularly magnificent, offering panoramic views of Ginkaku-ji Temple, Yoshida Mountain, the Kyoto University campus, and the city of Kyoto. It’s easy to imagine how the castle lords monitored the movements of Kyoto from this vantage point during the Sengoku period.
Access and Climbing Guide to Nyoigatake Castle
Main Hiking Routes
There are several hiking routes to Nyoigatake Castle (Daimonji Mountain).
Ginkaku-ji Route (Most Common):
- Starting Point: Trailhead approximately 10 minutes on foot from Ginkaku-ji-michi bus stop
- Time Required: Approximately 40-50 minutes ascent
- Features: The most well-maintained route, suitable for beginners
- The trail is clear, and there are historical sites such as Senjinzuka along the way.
Keage Route:
- Starting Point: Trailhead near Keage Incline
- Time Required: Approximately 1 hour ascent
- Features: A somewhat steep climb, but offers a quiet mountain walk.
Nyoi-ji Route:
- Starting Point: Trailhead near the Nyoi-ji Temple ruins
- Time Required: Approximately 50 minutes ascent
- Features: A route that follows the old Nyoi-goe road, offering a historical atmosphere.
Precautions When Climbing
Clothing and Equipment:
- Hiking boots or trekking shoes are recommended
- Be especially careful as the trail can be slippery after rain.
- Please bring insect repellent in summer and warm clothing in winter.
Estimated Time:
- Ascent: 40-60 minutes
- Sightseeing at the summit: 30-60 minutes
- Descent: 30-40 minutes
- Total: Please allow approximately 2-3 hours.
Best Time to Visit:
- Spring (March-May) and Autumn (October-November) are ideal.
- Be aware of the heat and insects in summer.
- There is a possibility of snow and ice in winter.
- It is best to avoid visiting on August 16th (the day of the Obon fire ceremony) as it will be crowded.
Access by Public Transportation
Train and Bus:
- From Kyoto Station, take City Bus Route 5 or 100 and get off at “Ginkakuji-michi” (approx. 30 minutes).
- From Keage Station on the Tozai Subway Line, walk to the trailhead (approx. 15 minutes).
Parking:
- There are paid parking lots around Ginkakuji Temple, but they are crowded on holidays.
- We recommend using public transportation.
Nearby Historical Spots
Ginkaku-ji Temple (Jisho-ji Temple)
Located at the western foot of Nyoigatake Castle, Ginkaku-ji Temple is a symbol of Higashiyama culture, built by Ashikaga Yoshimasa, the 8th shogun of the Muromachi shogunate. While Nyoigatake Castle functioned as a military base, Ginkaku-ji Temple was a center of culture. This contrast illustrates the duality of Kyoto during the Muromachi period.
Nyoi-ji Temple Ruins
The Nyoi-ji Temple ruins, located south of Nyoigatake Castle, are the remains of a temple that flourished from the Heian period to the Muromachi period. Although only scattered stone walls and foundation stones remain today, they allow us to imagine its former scale.
Yoshida Mountain and Yoshida Shrine
To the west of Nyoigatake Castle lies Yoshida Mountain, where Yoshida Shrine is located at the summit. Yoshida Mountain was also used militarily in the Middle Ages, forming a defensive line in eastern Kyoto in conjunction with Nyoigatake Castle.
Nanzenji Temple
When using the Keage route, you can pass through Nanzenji Temple. Nanzenji Temple is the head temple of the Nanzenji branch of the Rinzai school of Zen Buddhism, and during the Muromachi period, it was a prestigious temple ranked among the top five temples of Kyoto.
Historical Significance of Nyoigatake Castle
Character as a Camp Fortress
Nyoigatake Castle was not a permanent residence, but rather a “camp fortress” where troops were temporarily stationed during battles. Historical records confirm that it was used by different forces over time, including Taga Takatada, Hosokawa Sumimoto, Miyoshi Yukinaga, Hosokawa Takakuni, and Ashikaga Yoshiteru.
This form of use indicates that Nyoigatake Castle was not a base of control for a specific lord, but was recognized as a strategically important point in the struggle for control of Kyoto, the political center.
Repeated Renovations and Expansions
The remaining structures are not thought to have been built in a single period, but rather were gradually renovated and expanded through multiple battles.
In particular, the scale of the moats and earthworks suggests that a major renovation was carried out during the battle of Eisho 6 (1509), and it is presumed that further modifications were made during subsequent periods of encampment, such as Eisho 17 (1520) and Eiroku 1 (1558).
This multi-layered structure indicates that Nyoigatake Castle was not merely a temporary encampment, but an important base that was repeatedly used.
Its Place in Kyoto’s Military History
Nyoigatake Castle played a crucial role in Kyoto’s military defense system. From the Onin War to the Sengoku period, Kyoto was constantly under military tension and needed to prepare for invasions from the east.
Nyoigatake Castle functioned as a forward base to monitor forces from the Omi region and intercept them when necessary. The existence of this castle allowed the rulers of Kyoto to constantly monitor developments in the east, maintaining a strategic advantage.
Cultural Value
The Kyoto Prefectural Board of Education has designated the Nyoigatake Castle ruins as an important medieval castle site. The castle, with its well-preserved large-scale moat and earthworks surrounding the mountaintop, is highly valued academically.
Currently, detailed surveys and excavations are limited, but future research is expected to reveal much more about the evolution of castle technology from the Muromachi period to the Sengoku period, and about the military history of Kyoto.
Preservation of Nyoigatake Castle and Future Challenges
Current Status and Preservation Condition
While the Nyoigatake Castle ruins are used by many people as a hiking trail, their recognition as a castle site is not necessarily high. Therefore, some of the remains may be affected by the maintenance of the hiking trail and the upkeep of the Daimonji bonfire.
However, because large-scale development has not taken place, the main remains are preserved in relatively good condition. In particular, the moats and earthworks retain much of their original form from the time of construction, making them valuable historical relics.
Need for Future Investigation and Research
While research on Nyoigatake Castle has progressed based on historical documents, archaeological investigations are still insufficient. Further detailed surveys and limited excavations could potentially reveal the following:
- The extent of renovations and changes in construction techniques during each period
- The layout of buildings and daily life within the castle
- Specific uses during battles
- Relationship with Nyoi-ji Temple
These studies are crucial for understanding the military history of Kyoto from the Muromachi period to the Sengoku period.
Utilization as a Tourism Resource
Nyoigatake Castle, located near the easily accessible hiking spot of Daimonji Mountain, has great potential as a historical tourism resource. Currently, explanatory signs for the ruins are limited, but the following initiatives are expected in the future:
- Installation of detailed explanatory signs for major ruins
- Development of a viewing route combining hiking trails and castle ruins
- Introduction of an explanatory system utilizing smartphone apps, etc.
- Implementation of regular guided tours
These initiatives could lead to greater recognition of the historical value of Nyoigatake Castle and its development as a new historical tourist spot in Kyoto.
Summary
Nyoigatake Castle is a mountain castle that played an important role as a strategic point connecting Kyoto and Omi from the Onin War to the Sengoku period. Because it is built on the easily accessible Daimonji Mountain, many hikers visit, but its historical value is not yet fully known.
The large-scale moats and earthworks surrounding the mountaintop remain remarkably well-preserved even after more than 500 years, making them valuable ruins that allow visitors to directly experience the castle construction techniques of the Sengoku period. Important historical figures such as Taga Takatada, Hosokawa Sumimoto, Miyoshi Yukinaga, Hosokawa Takakuni, and Ashikaga Yoshiteru used this castle and waged battles for control of Kyoto.
By visiting Nyoigatake Castle, you can understand Mount Daimonji not only from the cultural perspective of the Gozan Okuribi (five mountain bonfires), but also from a new perspective of Kyoto’s military history. As an attractive spot combining hiking and historical exploration, why not visit it at least once?
By observing the castle ruins and reflecting on Kyoto during the Sengoku period, you can experience living history that you can’t learn from textbooks. Nyoigatake Castle is a valuable historical heritage site that conveys a little-known aspect of Kyoto’s history.
