Mochizuki Castle: A Complete Guide to its History and Highlights | A Thorough Explanation of the Famous Castle in Saku City, Nagano Prefecture
Table of Contents
- Overview of Mochizuki Castle
- History and Development of Mochizuki Castle
- Genealogy of the Mochizuki Clan and the Shigeno Family
- Castle Structure and Layout
- Main Remains and Highlights
- Takeda Shingen’s Invasion of Saku and Mochizuki Castle
- Sanada Yukitaka’s Mediation and Surrender
- Preservation of Mochizukiyama Castle and Castle Ruins
- Access and Visiting Guide
- Surrounding Tourist Information
Overview of Mochizuki Castle
Mochizuki Castle is a Korean mountain castle located in Mochizuki, Saku City, Nagano Prefecture. It is known as the residence of the Mochizuki clan, a powerful family that ruled the Mochizuki region of Saku County in Shinano Province during the Sengo
The elevation of the main cast enclosure is approximately 780m, while the elevation of the town is around 670m, resulting in a relative height of approximately 110m. This is a large mountain castle, stretching approxim and the third enclosure are clearly constructed, and the southern subsidiary castle has been identified as having up to the fifth enclosure.
As a magnificent and sturdy mountain castle, the lower enclosures, belt enclosures, and dry moats are neatly constructed, and it is relatively well-preserved. The structure, with the main enclosure to the north and the secondary enclosure to the south, is a type
History and Background of Mochizuki Castle
Construction History
There are various theories regarding the construction date of Mochizuki Castle, but it is believed to have been built by the Mochizuki clan, a branch of the Shigeno clan. The most likely theory is that after Tenjin Castle fell to an attack by Ogas Castle was built as a new base.
The Mochizuki clan played an active role in the Hogen Rebellion (1156) and is said to have held an important position in the shogunate during the Kamakura period. As one of the three prominent Shigeno families, the Mochizuki clan had established a powerful position
Turmoil of the Sengoku Period
During the Sengoku period (Warring States period), Mochizuki Castle became a battleground between the Takeda clan of Kai Province and local forces in Shinano Province. In 1543, when Takeda Harunobu (later Shingen) launched his full-sca a target.
Although Mochizuki Castle fell to the fierce Takeda army’s assault, the Mochizuki clan continued to resist. However, through the mediation of Sanada Yukitaka (Yukitsuna), also a member of the Shigeno clan, the the-lord of the castle, Mochizuki Moritoki,
The Era under the Takeda Clan
After surrendering, the Mochizuki clan continued to use Mochizuki Castle as their residence as local lords under the Takeda clan. They are believed to have played an important role in governing the Saku region within the Takeda clan’s control of Shinano Province.
Remains from the Takeda clan’s rule still exist today, confirming that the castle underwent expansion and renovation. It is presumed that the castle continued to function during the Tensho era (1573-1592).
The Castle’s End
There are few historical records regarding the fate of Mochizuki Castle after the fall of the Takeda clan in 1582, and many details remain unknown. It is believed that its role as a mountain castle ended with the end of the Sengoku period.
The Genealogy of the Mochizuki Clan and the Shigeno Family
The Three Shigeno Families
The Shigeno clan was a powerful local family in Shinano Province, expanding its influence from the Heian period to the Kamakura period. The Three Shigeno Families refer to the Mochizuki, Unno, and Nezu (Nezu) clans, which branched off from the Shigeno clan.
These three families controlled the region from Saku County to Chiisagata County and are known as important forces in medieval Shinano. The Mochizuki clan, in particular, was based in the Mochizuki region of Saku County and was known as the administrator of the Mochizuki Pasture (an imperi
Historical Role of the Mochizuki Clan
The Mochizuki clan served Minamoto no Yoritomo from the time of the establishment of the Kamakura Shogunate and played an active role as gokenin (vassals). They distinguished themselves in the Hogen Rebellion and the Heiji Rebellion, and are said to have maintain the Kamakura period.
During the Muromachi period, they maintained their power through their relationships with the shugo daimyo (provincial governors) and continued to exist as local lords of the Mochizuki region until the Sengoku period (Warring States period).
Relationship with the Sanada Clan
Sanada Yukitaka (Yukitsuna) is also said to have been from the Shigeno clan, and was related to the Mochizuki clan. This kinship is thought to be the background to Sanada Yukitaka’s role as mediator during Takeda Shingen’s invasion of Saku.
The fact that Mochizuki Moritoki surrendered to the Takeda clan through the mediation of the Sanada clan is noteworthy as an example of cooperation within the Shigeno clan and a survival strategy in the Sengoku period.
Castle Structure and Layout
Overall Layout
Mochizuki Castle is a large mountain castle stretching approximately 1500m from north to south. The main section centers around the main enclosure on the north side, with the secondary, second, and third enclosures arranged in succession.
The southern branch castle section also includes the fourth and fifth enclosures, resulting in a complex layout with multiple enclosures organically connected. Taking advantage of its 110m elevation, the design is characterized by a balance between defense and habitability.
Structure of the Main Enclosure
The main enclosure is located at the highest point of the castle and is presumed to have housed the lord’s residence and command post. Earthen ramparts surrounded it, and the entrance (koguchi) was heavily fortified.
From the main enclosure, one can see a panoramic view of the Saku Plain, indicating its function as a military observation post. The shape of the enclosures is relatively close to a regular square, suggesting planned construction.
Secondary Enclosures and Continuous Enclosures
Located south of the main enclosure, the secondary enclosure is the second most important section after the main enclosure. A moat separates it from the main enclosure, creating a structure that maintains independence while allowing for coordination.
The second and third enclosures are arranged in a stepped fashion, each reinforced by lower enclosures and belt enclosures. This continuous arrangement created a multi-layered defensive system that prevented enemy incursions in stages.
Defensive Structures
Mochizuki Castle retains numerous defensive structures typical of medieval mountain castles, including dry moats, trenches, earthworks, and vertical moats. The dry moats, in particular, are large in scale, some reaching several meters in depth.
The lower enclosures are arranged to surround the main enclosures, increasing the thickness of the defenses and also functioning as waiting areas for soldiers. The belt enclosures are long and narrow, built along the castle walls, and areth 이동.
Main Remains and Highlights
Well-Preserved Remains
The remains of Mochizuki Castle are relatively well-preserved, with the baileys and dry moats clearly visible. Because there was little destruction due to later development, it is valued as a valuable site that allows us to imagine the castle’s app
In particular, the earthworks and moats around the main bailey are clearly visible, making them important resources for learning about the structure of mountain castles during the Sengoku period.
Group of Baileys
Multiple baileys have been identified from the main bailey to the fifth bailey. Each bailey differs in size and shape according to its purpose, indicating the functional layout of the castle.
The flat areas of the baileys are relatively large, and there are several places where building remains may exist. It is expected that further archaeological excavations will reveal more detailed information about the castle’s use.
Dry Moats and Moats
Multiple dry moats were constructed within the castle, and the moats separating the baileys are also clearly visible. These functioned as important defensive lines to prevent enemy intrusion.
The bottom of the moat remains deep, allowing us to appreciate its former scale. Earthen bridges were constructed across some of the moats, indicating they also served as passageways.
Earthworks
Earthworks surround the main and secondary enclosures. While their height varies, many are around 1-2 meters high. It is presumed that fences or walls were built on top of these earthworks.
Observing the structure of the earthworks reveals meticulous construction using the rammed earth method, demonstrating the high level of castle construction technology.
Entrances (Koguchi)
The entrances to each enclosure, known as koguchi, feature complex structures emphasizing defense. Instead of straight lines, the inclusion of turns and bends makes enemy intrusion difficult.
Traces of stonework have been found at some koguchi, indicating that important entrances were particularly heavily fortified.
Takeda Shingen’s Invasion of Saku and Mochizuki Castle
Background of the Saku Invasion
After unifying Kai Province, Takeda Harunobu (Shingen) began his full-scale expansion into Shinano Province. Saku County, adjacent to Kai Province, was strategically important as a foothold for controlling Shinano.
The full-scale invasion of Saku began in 1542, and in the following year, 1543, Mochizuki Castle also became a target.
The Battle of Mochizuki Castle
The Takeda army’s invasion of Saku was fierce, and many local forces resisted. Mochizuki Castle initially resisted the Takeda army, but was forced into a difficult battle against their overwhelming military strength.
Although the castle’s strong defenses prevented its easy fall, it is believed that the prolonged siege and the surrender of surrounding forces led to its isolation.
Fall of the Castle
In 1543 (Tenbun 12), Mochizuki Castle fell to an attack by the Takeda army. However, the Mochizuki clan did not completely surrender and continued to resist.
Detailed historical records of the battles during this period are scarce, and many aspects of the specific battles remain unclear. However, it is certain that this was an important battle in establishing the Takeda clan’s control over Saku.
Mediation and Surrender by Sanada Yukitaka
Role of Sanada Yukitaka
Sanada Yukitaka (Yukitsuna) played a crucial role in the conquest of Shinano as a senior retainer of Takeda Shingen. He particularly utilized his background as a member of the Shigeno clan, demonstrating skill in persuading and strategizing his own clan.
In negotiations with the Mochizuki clan, the bond of being from the same Shigeno clan was a crucial factor. It is believed that Yukitaka persuaded the Mochizuki clan to submit to the Takeda clan.
Mochizuki Moritoki’s Decision
Mochizuki Moritoki, the lord of the castle at the time, accepted the mediation of Sanada Yukitaka and decided to surrender to the Takeda clan. This decision was a practical choice to preserve the Mochizuki family name and territory.
The fact that Mochizuki Castle was allowed to remain as their residence even after the surrender indicates that the Takeda clan valued the Mochizuki clan’s ability to govern the region.
The Mochizuki Clan under the Takeda Clan
After becoming a vassal of the Takeda clan, the Mochizuki clan took on the role of governing the Saku region as local lords. In the Takeda clan’s system of control over Shinano Province, the cooperation of local forces was indispensable, and the Mochizuki clan played an important role
Mochizuki Castle also functioned as part of the Takeda clan’s castle network, and it is possible that it underwent renovations and expansions. Some of the existing remains are thought to date from this period.
Preservation of Mochizukiyama Jōkōin Temple and the Castle Ruins
History of Mochizukiyama Jōkōin Temple
At the foot of Mochizuki Castle is a temple called Mochizukiyama Jōkōin. This temple is said to have had a deep connection with the Mochizuki clan and is an important site that tells the history of the castle.
Jōkōin Temple still exists today and serves as one of the entrances to the Mochizuki Castle ruins. A path to the castle ruins is maintained from the temple grounds, making it convenient for visitors.
Cultural Value
Mochizuki Castle ruins are highly regarded as one of the best-preserved medieval mountain castles in Nagano Prefecture. Because the remains are clearly visible, it is an important resource for castle research and history education.
Currently, information boards have been installed at some of the remains, and improvements are being made to make it easier for visitors to understand the castle’s structure.
Efforts for Preservation and Utilization
The local Saku City and Saku Regional Union are working on the preservation and utilization of the Mochizuki Castle ruins. They are conducting surveys and maintenance of the remains, and are also considering its use as a tourist resource.
Improvements are being made to create an environment that welcomes visitors, such as improving access roads to the castle ruins and installing information signs. Further archaeological excavations and academic research are expected to reveal the full extent of the castle.
Access and Visiting Guide
Location
Address: Shiro, Mochizuki, Saku City, Nagano Prefecture
Elevation: Approximately 780m (main castle enclosure)
Relative Height: Approximately 110m (from Jōkōin Temple)
Access by Car
Using the Jōshin-etsu Expressway:
- Approximately 15km from Saku IC, about 25 minutes by car
- Approximately 12km from Saku Minami IC, about 20 minutes by car
Using the Chūbu-dan Expressway:
- Approximately 20 minutes from Saku Minami IC via National Route 142
Parking: There is some parking space around Jōkōin Temple. Space is limited, so caution is advised during busy periods.
Access by Public Transportation
Using the JR Koumi Line:
- Get off at Kita-Nakagomi Station on the JR Koumi Line, then take a taxi for approximately 15 minutes.
- Get off at Nakagomi Station on the JR Koumi Line, then take a taxi for approximately 20 minutes.
Local Buses: Bus services to the Mochizuki area are limited, so it is recommended to check the timetable in advance.
Precautions When Visiting the Castle
Clothing and Equipment:
- As it is a mountain castle, appropriate clothing and shoes for mountain climbing are necessary.
- Non-slip trekking shoes are recommended.
- Bring insect repellent in summer and warm clothing in winter.
Estimated Time Required:
- Approximately 30-40 minutes on foot from Jōkōin to the main enclosure.
- Allow approximately 2-3 hours round trip, including sightseeing inside the castle.
Safety Precautions:
- Be careful of your footing as there are some steep slopes and areas prone to landslides.
- Avoid visiting alone; it is recommended to visit with multiple people whenever possible.
- Refrain from visiting on days with bad weather or during snowfall in winter.
Best Time to Visit:
- Spring to autumn (April to November) is the best time to visit.
- Winter (December to March) may have snow or ice, making it suitable for experienced climbers.
Preparation for Your Visit
Pre-Visit Checks:
- Check the weather forecast and choose a sunny day.
- We recommend obtaining the latest information from the local tourist information center.
- Cell phone reception may be unstable depending on the location.
Things that are useful to bring:
- Drinking water (there are no vending machines around the castle ruins)
- Snacks or energy supplements
- Camera (for documenting the ruins)
- Map or guidebook
- First-aid kit
Nearby Tourist Information
Historical Spots in Saku City
Ryūoka Castle Goryōkaku: Located about 30 minutes by car from Mochizuki Castle, it is one of only two Goryōkaku (square-shaped fortifications) in Japan. It is a Western-style castle built during the late Edo period
Former Nakagomi School: Built in 1875 (Meiji 8), it is one of the oldest existing Western-style school buildings and is designated as a national important cultural property. It is about 20 minutes by car from Mochizuki Castle.
Saku City Mochizuki Historical and Folk Museum: A museum introducing the history and culture of the Mochizuki area, including exhibits related to Mochizuki Castle. Visiting these sites before or after your castle visit will deepen your understanding.
Nearby Castle Ruins
Tenjin Castle Ruins: This castle is believed to be the residence of the Mochizuki clan before Mochizuki Castle. It is a historical site where the castle is said to have fallen in 1335.
Uchiyama Castle Ruins: One of the medieval mountain castles in the Saku region, it, like Mochizuki Castle, was invaded by the Takeda clan. It is suitable for comparative viewing.
Kasuga Castle Ruins: Another medieval mountain castle located in Saku City, it has a history related to the Takeda clan. Visiting it together with Mochizuki Castle will deepen your understanding of the castle history of the Saku region.
Hot Springs and Accommodations
Mochizuki Onsen: There are hot spring facilities in the Mochizuki area, perfect for relaxing after visiting the castle. Day trips are also possible.
Hotels and Ryokans in Saku City: There are many hotels and ryokans in the Saku city center, making it a convenient base for sightseeing. This hotel can be used as accommodation for sightseeing in Saku, including a visit to Mochizuki Castle.
Food & Local Products
Saku Carp Cuisine:
Saku is famous for its carp dishes. You can enjoy traditional local cuisine such as carp stew and sweet simmered carp.
Soba Noodles:
As the home of Shinshu soba noodles, there are many delicious soba restaurants scattered around the Mochizuki area.
Highland Vegetables:
Saku is a production area for highland vegetables, and you can purchase fresh vegetables at direct sales outlets.
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Mochizuki Post Town Festival:
This festival is held in Mochizuki, a post town that flourished on the Nakasendo road. You can enjoy the historical atmosphere.
Historical Events in Saku City:
Saku City holds various historical events throughout the year. We recommend checking the city’s tourist information before your visit.
Summary
Mochizuki Castle is a magnificent mountain castle built by the Mochizuki clan, one of the three Shigeno families. It is a valuable medieval mountain castle site with a large-scale layout spanning approximately 1500m. Having experiend a Shingen’s invasion of Saku—and surviving as a local lord under the Takeda clan through the mediation of Sanada Yukitaka, it serves as a prime example of survival strategies for local forces during the Sengoku period.
The remaining structures, including the baileys from the main enclosure to the fifth bailey, and the clearly preserved dry moats and earthworks, are valuable historical assets that convey the castle’s appearance at the time of its construction. The highly defen elevation, and the orderly arrangement of baileys, make it an important resource for learning about typical medieval mountain castles.
When visiting Saku City, Nagano Prefecture, be sure to visit the Mochizuki Castle ruins and feel the spirit of the Sengoku period. Walking through the well-preserved remains will allow you to experience the reality of history in a way that textbooks cannot.
When visiting, please prepare appropriate clothing and equipment, take safety precautions, and cooperate in preserving this valuable historical site for future generations. Mochizuki Castle is a famous castle that holds an important place in the history of Korean castles, and its value.
