Kasagi Castle: A Complete Guide to the History and Highlights of the Mountain Castle Where Emperor Go-Daigo Held a Stable
Located in Kasagi-cho, Soraku-gun, Kyoto Prefecture, Kasagi Castle is a historically significant mountain castle that served as a base for Emperor Go-Daigo’s campaign to overthrow the Kamakura Shogunate during the Genkō War. Built on the steep Mt. Kasagi (approximately 288 meters above sea level) on the left bank of the Kizu River, this castle is known as a unique structure in castle history, having been constructed using the mountain temple, Kasagi-dera.
History of Kasagi Castle
The Genkō War and Emperor Go-Daigo’s Uprising
Kasagi Castle first appeared on the historical stage in Genkō 1 (1331). Emperor Go-Daigo, who was planning to overthrow the Kamakura Shogunate, fled Kyoto on August 27th after learning that his plan had been leaked, and first entered Kintai-ji Temple on Mt. Washimine. Subsequently, in order to forge alliances with the Nanbu forces, they chose Mount Kasagi, a more strategically located site, and began a siege, using Kasagi-dera Temple as their temporary residence.
This was a groundbreaking example in the history of castles, being the first time a mountain temple was used as a mountain castle, and it became a precursor to the mountain temple castles of the later Nanboku-cho period. Mount Kasagi was a natural stronghold, surrounded by the Kizu River and sheer cliffs, possessing terrain well suited for defense.
The Battle of Mount Kasagi
In September of the first year of the Genkō era (1331), the Kamakura Shogunate dispatched a large army to besiege Kasagi Castle. The Shogunate forces were a large army centered around the Rokuhara Tandai, including samurai groups dispatched from the Kanto region. On the other hand, Emperor Go-Daigo’s side continued to resist, coordinating with Kusunoki Masashige, the lord of Akasaka Castle, and others.
Particularly famous in the battle was the exploits of Asuke Shigenori. He is said to have surprised the shogunate army with his unconventional tactic of throwing arrows by hand. A monument recreating this battle of Asuke Shigenori stands in front of JR Kasagi Station, commemorating the Battle of Mount Kasagi.
After a siege lasting approximately one month, Kasagi Castle fell on the night of September 28th during a night attack by the shogunate army. Emperor Go-Daigo attempted to escape the mountain but was captured and exiled to Oki Island. This defeat was temporary; Emperor Go-Daigo later escaped from Oki and ultimately succeeded in overthrowing the Kamakura Shogunate.
Kasagi Castle in the Sengoku Period
Approximately 200 years after the Genkō War, during the Sengoku period, Kasagi Castle reappeared on the historical stage. In Tenbun 10 (1541), Kizawa Nagamasa, the deputy governor of Kawachi Province, entered Kasagi Castle and renovated it as a fortress.
Nagamasa Kizawa was a Sengoku-period daimyo who sought to expand his power and developed Kasagi Castle as a military base. It is believed that defensive structures characteristic of the Sengoku period, such as moats and earthworks, were added during this time. Many of the remains that can be confirmed today are thought to date from this renovation by Nagamasa Kizawa.
However, Nagamasa Kizawa was defeated and killed in the Battle of Taiheiji in 1542, and much of the detailed history of Kasagi Castle after that remains unknown.
Structure and Characteristics of Kasagi Castle
Unique Layout Utilizing a Mountain Temple
The most distinctive feature of Kasagi Castle is that it utilized the existing layout of the Kasagi-dera temple complex. Kasagi-dera is an ancient temple said to have been visited by Ryōben, who was involved in the construction of Tōdai-ji temple during the Nara period, and his disciple Jitchū, and the entire mountain was an object of worship.
The castle grounds spread mainly around the summit of Mount Kasagi, and most of it is currently designated as National Historic Site and Place of Scenic Beauty, Mount Kasagi. The elevation difference is approximately 200 meters, and the steep slope from the Kizu River serves as a natural defensive wall.
Honmaru and Ninomaru
Honmaru is the site of Emperor Go-Daigo’s residence. This is the central part of Kasagi-dera Temple and remains a place visited by worshippers today. On the other hand, the area known as Ninomaru is believed to be the site of Emperor Go-Daigo’s temporary imperial residence and is known as the site of his temporary residence.
These enclosures, while based on the layout of temple buildings, show numerous defensive features.
Highlights of the Remains
The main remains that can be confirmed today include the following:
Yokobori: A yokobori (horizontal moat), believed to have been built during the Sengoku period when Kizawa Nagamasa renovated the temple, remains on the mountainside. This was an important defensive structure to prevent enemy intrusion.
Earthworks: Traces of earthworks can be seen around the enclosures, indicating that they formed a defensive line.
Cliffs: Cliffs, carved into the already steep terrain, can be seen in various places, a clever design intended to hinder the advance of attackers.
Fortification Remains: The remains of the fortifications that served as entrances to the castle are still visible, allowing us to imagine the castle’s structure in its heyday.
Cultural Properties of Kasagi-dera Temple
When visiting the castle ruins, don’t miss the cultural properties of Kasagi-dera Temple. Particularly famous are the rock-carved Buddhas, awe-inspiring images of Buddhas carved into massive rocks. Although many buildings were destroyed by fire during the Genkō War, these stone structures still convey the temple’s original appearance.
Access and Visiting Guide to Kasagi Castle
Transportation Access
Access by Train:
- Get off at JR Kansai Main Line “Kasagi Station,” then walk approximately 45 minutes to the entrance of Kasagi-dera Temple.
- From Kasagi Station to Mount Kasagi, use the hiking trail.
Access by Car:
- Use National Route 163; parking is available in Kasagi Town.
- For car navigation, searching for “Kasagi-dera Temple” is convenient.
Admission Fee and Opening Hours
The admission fee for Kasagi-dera Temple is approximately 300 yen for adults (may vary depending on the season). Since visiting the castle ruins requires passing through the temple grounds, an admission fee is required.
Visiting hours are usually from sunrise to sunset, but it is recommended to check the details in advance.
Estimated Visiting Time and Points to Note
It is advisable to allow 2-3 hours for visiting the Kasagi Castle ruins. As this is a mountain castle, please note the following:
- Hiking Equipment: Comfortable clothing and non-slip shoes are essential.
- Drinking Water: There are no vending machines on the mountain, so prepare in advance.
- Season: Take precautions against the heat in summer and warm clothing in winter.
- Weather: Be careful as the ground can become slippery in rainy weather.
Nearby Attractions
Monument in front of Kasagi Station
In front of JR Kasagi Station, there is a monument depicting Asuke Shigenori throwing an arrow. It is a valuable resource for visually understanding the Battle of Kasagi Mountain.
Scenery of the Kizu River
The Kizu River, flowing at the foot of Mount Kasagi, offers beautiful valley scenery. The autumn foliage season is particularly spectacular and can be enjoyed in conjunction with a visit to the castle ruins.
Nearby Castles
If you visit Kasagi Castle, we recommend exploring the surrounding castles as well:
- Yagyu Castle: The residence of the Yagyu clan, renowned swordsmen
- Yagyu Old Castle: The former castle of the Yagyu family
- Yagyu Jinya: The site of the Yagyu Domain’s administrative office
These castles are relatively close to Kasagi Castle and are popular as part of a mountain castle tour.
Historical Significance of Kasagi Castle
The Starting Point of the Nanboku-cho War
Kasagi Castle was the stage of the Genko War, a crucial turning point in Japanese history. Emperor Go-Daigo’s uprising here marked the fall of the Kamakura Shogunate, the Kenmu Restoration, and the beginning of the turbulent Nanboku-cho period.
Pioneer of Mountain Temple Castles
Kasagi Castle holds an important position in castle history as one of the earliest examples of a mountain temple being used as a castle. This technique was adopted in various regions during the later Nanboku-cho period, leading to the construction of many mountain temple castles, such as Kongoji Castle, Chihaya Castle, and Akasaka Castle.
Local Historical Heritage
For Kasagi Town in Soraku District, southern Kyoto Prefecture, Kasagi Castle and Mount Kasagi are important historical heritage sites that form the region’s identity. The town is focusing on the preservation and utilization of Mount Kasagi, and the Kyoto Prefectural Board of Education Cultural Properties Protection Division is also involved in the management of the historical site.
Current Status of Kasagi Castle Research
Recent archaeological excavations and research are gradually revealing the true nature of Kasagi Castle. In particular, the renovated sections by Kizawa Nagamasa during the Sengoku period offer insights into the castle construction techniques of the time, based on remains such as moats and earthworks.
However, due to limited historical materials, many aspects of the castle’s structure during the Genko War remain unclear. Further research is anticipated.
Summary
Kasagi Castle is a historical mountain castle where Emperor Go-Daigo holed up to overthrow the Kamakura Shogunate, and it is a valuable historical site where you can experience a turning point in Japanese history: the Genkō War. It boasts a unique castle structure utilizing the mountain temple Kasagi-dera, natural fortifications due to the Kizu River and steep terrain, and remnants of renovations carried out by Kizawa Nagamasa during the Sengoku period, offering plenty to see.
It is easily accessible on foot from JR Kasagi Station, and you can freely explore it after paying an entrance fee, making it a convenient place for history buffs and castle enthusiasts. Why not experience the romance of medieval history on Mount Kasagi, which is protected as a cultural property of Kyoto Prefecture?
As you climb the rugged terrain characteristic of mountain castles, imagining the scene of Emperor Go-Daigo and Asuke Shigenori fighting there will deepen your understanding of history. Kasagi Castle is not merely a castle ruin; it continues to fascinate many people as a place that significantly shaped Japanese history.
