Complete Guide to Ishigami Castle (Ibaraki Prefecture): The Residence and Remains of the Ishigami-Onozaki Clan, Supporters of the Satake Clan
Ishigami Castle, located in Tokai Village, Naka District, Ibaraki Prefecture, is a flatland castle that served as the residence of the Ishigami-Onozaki clan, who were important retainers of the Satake clan during the Sengoku period. Currently, it is maintained as Ishigami Castle Ruins Park, and the remains such as earthworks and moats are well-preserved, making it an important historical site for understanding medieval castles in Ibaraki Prefecture. This article provides a detailed explanation of Ishigami Castle’s history, structure, highlights, and access information.
History of Ishigami Castle and the Ishigami-Onozaki Clan
Construction of Ishigami Castle and the Establishment of the Ishigami-Onozaki Clan
Ishigami Castle is believed to have been built by Onozaki Michio. The Onozaki clan was a powerful samurai group in Hitachi Province, and its family was divided into several branches. The Ishigami Onozaki clan was one such example, establishing a castle on a plateau on the right bank of the Kuji River estuary and making it their base of operations in the region.
While there are various theories about the Onozaki clan’s origins, they are generally believed to have descended from the Hitachi Taira clan and expanded their power in northern Hitachi Province from the Kamakura period to the Muromachi period. The Ishigami clan is thought to have established their base in Ishigami in the late 15th or early 16th century.
Conflict and Conflict with the Nukada Onozaki Clan
An essential part of the history of the Ishigami Onozaki clan is their conflict with the Nukada Onozaki clan, a related family. The Nukada clan was also a branch of the Onozaki clan and was based at Nukada Castle, located south of Ishigami Castle.
Despite being related, the two clans frequently clashed, repeatedly fighting over territory and spheres of influence. This conflict is thought to have stemmed from factors such as the need to expand their power in limited areas and differences in loyalty to their lord, the Satake clan. Particularly during the late Sengoku period, the conflict between the two clans intensified, significantly impacting the regional political situation.
Loyalty to the Satake Clan and the Role of Ishigami Castle
From the mid-16th century onward, the Satake clan rapidly expanded its power in northern Hitachi Province. The Ishigami Onozaki clan pledged allegiance to the Satake clan early on and supported their expansion as important retainers.
On the other hand, the Nukata Onozaki clan was not always obedient to the Satake clan and sometimes acted independently. After Toyotomi Hideyoshi’s siege of Odawara in 1590, the Nukata clan ultimately chose to break away from the Satake clan. In contrast, the Ishigami clan consistently supported the Satake clan.
Ishigami Castle was located at the eastern edge of the Satake clan’s sphere of influence and was an important base controlling the Kuji River estuary area near the Pacific Ocean. It is believed to have held a strategically important position in managing maritime traffic and the distribution of goods.
The Keichō Relocation and the Ishigami Clan’s Transfer to Akita
In 1602, following the Battle of Sekigahara, Satake Yoshinobu was ordered by Tokugawa Ieyasu to undergo a significant reduction in territory and transfer from Hitachi Province (540,000 koku) to Akita in Dewa Province (200,000 koku). Many of the Satake clan’s retainers accompanied him on this transfer.
Ishigami Michihiro, the head of the Ishigami Onozaki clan, remained loyal to his lord, the Satake clan, and accompanied them to Akita. As a result, Ishigami Castle was abandoned, marking the end of the Ishigami Onozaki clan’s rule over Ishigami, which had lasted for over 400 years.
The Ishigami clan, having moved to Akita, continued to serve the Satake clan, playing a significant role in the history of the Akita Domain.
Structure and Layout of Ishigami Castle
Location and Topographical Features
Ishigami Castle is located on the tip of a plateau approximately 19 meters above sea level, on the right bank of the Kuji River estuary, in the northern part of Tokai Village, Naka District, Ibaraki Prefecture. The eastern side of the plateau faces lowlands, resulting in a defensive layout that skillfully utilizes the natural terrain.
The plateau on which the castle stands has a significant elevation difference from the surrounding lowlands, making it difficult for attackers to climb. Furthermore, its proximity to the Kuji River provided convenient water transport, making it an advantageous location for the transportation of goods and the transmission of information.
Arrangement and Composition of Enclosures
Ishigami Castle is composed of multiple enclosures (kuruma). Based on the remains that can be confirmed today, it is believed that there were three main enclosures. These enclosures were separated by moats and functioned as independent defensive units.
The main enclosure (honmaru) is located on the highest part of the plateau and is presumed to have housed the lord’s residence and important facilities. The second and third baileys were positioned to protect the main enclosure, forming a tiered defensive line.
The size of each bailey was standard for a medieval local lord’s castle, suggesting that it served more as a base for regional control than as a site for large-scale battles.
Features of the Earthworks and Moats
The greatest highlight of Ishigami Castle is the well-preserved remains of its earthworks and moats. The earthworks were built surrounding the baileys, and while their height varies, the highest points reach over 3 meters.
The tops of the earthworks are flat, suggesting that fences or walls may have once been erected there. Furthermore, it is believed that passages were provided inside the earthworks, allowing soldiers to move around during defense.
The moats were dry moats (moats that did not hold water) and functioned as trenches separating the baileys. The moats are still several meters deep today, and are estimated to have been even deeper in the past. The bottom of the moat exhibits the shape of a Yagenbori (a type of moat with a V-shaped groove) or a Hakobori (a type of box-shaped moat), showcasing typical structures of medieval castles.
Entrances and Exits
The entrances to the castle, known as Koguchi (gates), were considered weak points in defense and were therefore constructed with particularly strong fortifications. At Ishigami Castle, the entrance area features ingenious designs such as curved earthworks and deep moats.
The entrance itself is not a straight entrance, but rather features elements of “Kuchigai Koguchi” (a type of curved entrance) and “Masugata Koguchi” (a square-shaped entrance), designed to allow for flanking fire. This structure made it difficult for enemies to easily penetrate the castle.
Development and Current Status of Ishigami Castle Ruins Park
Development as a Park
Currently, the Ishigami Castle ruins have been developed as “Ishigami Castle Ruins Park,” serving as a place of relaxation for local residents. Walking paths have been established within the park, allowing visitors to stroll through the castle ruins and view the remains.
During the restoration, the preservation of the remains was the top priority, and alterations to the earthworks and moats were kept to a minimum. Information boards and explanatory signs have been installed to help visitors understand the history and structure of Ishigami Castle.
The park has a parking lot, making it easily accessible by car. Basic facilities such as restrooms are also available, creating a comfortable environment for visitors.
Preservation Status of the Remains
The remains of Ishigami Castle are among the best-preserved medieval castles in Ibaraki Prefecture. The earthworks and moats, in particular, remain clearly visible, allowing visitors to imagine the castle’s appearance at the time of its construction.
While there are some later alterations and natural collapses, the overall layout and structure are well-preserved. Some parts of the remains are hidden by tree growth, but regular maintenance ensures that it does not hinder visitors.
It has been designated a cultural property by the Ibaraki Prefectural Board of Education, and appropriate preservation and management are expected in the future.
Highlights and Recommended Sightseeing Points of Ishigami Castle
The Earthen Embankment of the Main Enclosure
The most impressive remains of Ishigami Castle are the earthen embankments surrounding the main enclosure. Both in height and width, they are magnificent and impressive for medieval castle embankments. There are sections where you can walk on top of the embankment, allowing you to survey the surroundings from the perspective of the castle’s soldiers.
Observing the cross-section of the embankment reveals that it was constructed using a technique called rammed earth. It’s clear that a strong embankment was constructed by layering soil and compacting each layer.
The Impressive Moat
The moats separating the enclosures are remains that allow you to truly appreciate the defensive function of Ishigami Castle. Standing at the bottom of the deeply dug moat, combined with the height of the earthen embankments on both sides, you can feel the high level of its defensive capabilities.
The moats were not merely divisions, but powerful barriers that prevented enemy intrusion. Against enemies attempting to cross the moat, the castle could effectively defend itself by throwing arrows and stones from the earthen ramparts.
Flat Surfaces Inside the Enclosures
The interiors of each enclosure are leveled, allowing one to imagine the layout of buildings and facilities. The size of the main enclosure, in particular, indicates the presence of the lord’s residence, warehouses, and barracks.
Walking along the flat surfaces of the enclosures, one can contemplate life in a castle during the Sengoku period and the tense atmosphere of defense.
Surrounding Landscape
From Ishigami Castle, one can enjoy panoramic views of the surrounding landscape. The views towards the Kuji River and the Pacific Ocean demonstrate the castle’s strategic location, considering both the sea and the river.
On a clear day, one can see distant mountain ranges and the coastline, offering the pleasure of imagining what the Ishigami Onozaki clan saw and thought from this location.
Access and Visiting Information for Ishigami Castle
Location and Basic Information
Location: 1258 Ishigamiuchijuku, Tokai-mura, Naka-gun, Ibaraki Prefecture
Designation: Ibaraki Prefecture Designated Historic Site
Castle Classification: Hilltop Castle
Construction Period: Late 15th to Early 16th Century (Estimated)
Builder: Onozaki Michio
Main Lords: Ishigami Onozaki Clan
Year of Abandonment: 1602 (Keicho 7)
Access by Public Transportation
The nearest station is Tokai Station on the JR Joban Line. Ishigami Castle Ruins Park is approximately 3 kilometers from Tokai Station.
- Walking: Approximately 40 minutes on foot from Tokai Station
- Bus: Use the Tokai Village Community Bus, etc. (Please check with the Tokai Village Office for details)
- Taxi: Approximately 10 minutes by taxi from Tokai Station
Public transportation access is somewhat inconvenient, so we recommend using a rental car or taxi.
Access by Car
Access by car is the most convenient.
- Joban Expressway: Approximately 15 minutes from Hitachi Minami-Ota IC, approximately 20 minutes from Naka IC
- National Route 6: Follow the signs from the Tokai Village direction
Ishigami Castle Ruins Park has a free parking lot with space for approximately 10 regular cars.
Visiting Hours and Fees
- Visiting Hours: No specific restrictions (open as a park at all times)
- Admission Fee: Free
- Recommended Visiting Time: Approximately 30-60 minutes
As it is a park, you can visit freely. However, nighttime visits are not recommended for safety reasons.
Points to Note When Visiting
- Attire: Although the walking paths are well-maintained, we recommend wearing comfortable shoes.
- Season: In summer, vegetation can be overgrown, making it difficult to see the remains. Spring and autumn are the best times to visit.
- Weather: Caution is advised as the ground can become slippery in rainy weather.
- Insect Repellent: Mosquitoes and other insects are abundant in summer, so carrying insect repellent spray is recommended.
- Manners: Climbing on the ruins or damaging the earthworks is strictly prohibited.
Nearby Tourist Spots and Related Historical Sites
Nukata Castle Ruins
These are the ruins of the castle of the Nukata Onozaki clan, who were in conflict with the Ishigami Onozaki clan. Located approximately 10 kilometers south of Ishigami Castle, it is situated in Naka City. Nukata Castle also retains remnants of earthworks and moats, and visiting both Ishigami Castle and Nukata Castle will provide a deeper understanding of the Onozaki clan’s history.
Satake-ji Temple (Jofuku-ji Temple)
This temple in Hitachiota City is associated with the Satake clan. Known as the Satake clan’s family temple, it offers a valuable opportunity to learn about their history. This is a worthwhile spot to visit when tracing the footsteps of the Satake clan, whom the Ishigami Onozaki clan served.
Tokai Village Nuclear Science Museum
This science museum is located about 10 minutes by car from Ishigami Castle Ruins Park. It’s a facility where you can learn about the mechanisms of nuclear power and science and technology, and learn about the modern state of Tokai Village. You can enjoy the contrast between history and the present.
Muramatsuyama Kokuzo-do Temple
This is a representative temple of Tokai Village and is considered one of the three great Kokuzo temples in Japan. It’s about 15 minutes by car from Ishigami Castle Ruins Park, and you can visit historical buildings and cultural properties.
Historical Significance and Evaluation of Ishigami Castle
Regional Governance Structure of Medieval Hitachi Province
Ishigami Castle is an important historical site for understanding the structure of regional governance in medieval Hitachi Province. It reflects the complex political situation of the relationship between the Sengoku daimyo Satake clan and their vassal, the Ishigami Onozaki clan, a regional lord, and the conflict with the related Nukata Onozaki clan.
This castle holds historical value as a concrete example illustrating how local lords demonstrated loyalty to their lords and the competitive relationships within their own clans.
Position in the History of Castle Architecture
The layout and structure of Ishigami Castle are typical of flatland castles in the Kanto region from the 15th to 16th centuries. The structure, primarily using earthworks and moats rather than stone walls, clearly represents the characteristics of castle architecture during this period.
While it lacks the large-scale stone walls and keeps of later early modern castles, its defensive structure, skillfully utilizing the terrain, demonstrates the high level of technical expertise in medieval castle construction.
Contribution to the Study of the Satake Clan’s Retainers
The Ishigami Onozaki clan is an important case study in the study of retainers who accompanied the Satake clan during their relocation. The Ishigami clan’s unwavering loyalty to their lord and their decision to accompany them to Akita despite a significant reduction in their territory reflects the values of samurai from the late Sengoku period to the early Edo period.
On the other hand, the contrast with the Nukata clan, who broke away from the Satake clan, provides material for considering the reasons and backgrounds behind the different choices made by members of the same family.
How to Enjoy Your Visit to Ishigami Castle
A Stroll That Evokes Historical Romance
When strolling through Ishigami Castle Ruins Park, you can have a deeper experience by not just looking at the remains, but by reflecting on the Sengoku period. As you walk along the earthworks, try to imagine what the samurai of the Ishigami Onozaki clan saw and what they were trying to protect in this place.
The conflict with the Nukata clan, loyalty to the Satake clan, and the final relocation of their domain. Ishigami Castle was the stage for many historical events. A stroll while feeling the weight of its history is worth more than just sightseeing.
Photography Tips
Ishigami Castle is also a suitable spot for photography. The following points are especially recommended:
- Earthwork Ridge: The earthwork ridge against the blue sky makes for an impressive photograph.
- Depth of the Moat: An angle looking up from the bottom of the moat can convey the impressive defensive structure.
- Flat Surface of the Enclosure: A composition combining the expansive flat surface with the surrounding earthworks is effective.
- Seasonal Scenery: Enjoy the seasonal expressions, such as the fresh greenery of spring and the autumn foliage.
Visiting as a Castle Enthusiast
For castle enthusiasts, Ishigami Castle is worth visiting for the following reasons:
- Well-Preserved Earthworks and Moat: You can learn about the basic structure of a medieval castle.
- Compact Scale: It is easy to grasp the overall layout and understand the fortifications.
- Castle of a Local Lord: You can understand the reality of regional rule, which differs from the castles of daimyo (feudal lords).
- Historical Background: This allows us to consider the role of the Ishigami Onozaki clan as members of the Satake clan’s retainer group.
Bringing a map of the castle grounds and related books will deepen your understanding during your visit.
Summary: The Story of the Sengoku Period Told by Ishigami Castle
Ishigami Castle in Tokai Village, Ibaraki Prefecture, is not large in scale, but it is a valuable historical site where you can learn about the realities of regional rule during the Sengoku period, the loyalty of samurai, and the structure of medieval castles.
The history of the Ishigami Onozaki clan’s unwavering loyalty to the Satake clan and their obedience to their lord until the end conveys the way of life of samurai during the Sengoku period. On the other hand, the conflict with the related Nukata Onozaki clan illustrates the complex political situation of the Sengoku period.
Although Ishigami Castle is now maintained as a quiet park, the remains of the earthworks and moats still convey the tension and historical weight of over 400 years ago. When visiting Ibaraki Prefecture, be sure to visit Ishigami Castle and feel the spirit of the Sengoku period.
It’s relatively easy to access from the city center, making it possible to visit on a day trip. It’s a recommended spot not only for history buffs and castle enthusiasts, but also for those who want to enjoy a quiet stroll. Be sure to listen to the story of the Sengoku period that Ishigami Castle tells.
