Nakajima Castle (Choshi City, Chiba Prefecture) Complete Guide | History, Remains, and Highlights Explained in Detail
Nakajima Castle, located in Choshi City, Chiba Prefecture, is an important castle known as the residence of the Kaijo clan, who ruled this area from the medieval period to the Sengoku period. It is the largest medieval castle in the Choshi area, and its remains, such as earthworks and dry moats, are still well-preserved. This article provides a detailed explanation of everything you need to know before visiting Nakajima Castle, from its history and structure to its highlights and access information.
History and Construction Background of Nakajima Castle
Construction by the Kaijo Clan
There are various theories regarding the construction date of Nakajima Castle, but the most widely accepted tradition is that it was built during the Kenkyu era (1190-1199) by Kaijo Yoichi Tsunehira, a member of the Higashi clan, one of the six Chiba clans. The Kaijo clan was a powerful branch of the Chiba clan that ruled the Choshi region from the Kamakura period, and they developed Nakajima Castle as their base of operations in the area.
The Chiba Six Clans refer to the branches of the Chiba clan that held power in Shimosa Province (present-day northern Chiba Prefecture) from the late Heian period to the Kamakura period. Among them, the Kaijo clan played a crucial role in controlling the Tone River estuary, a strategically important transportation and military location. Nakajima Castle functioned precisely as the headquarters of the main Kaijo family.
Developments during the Sengoku Period
With the arrival of the Sengoku period, the Kaijo clan chose to submit to the Later Hojo clan, who became the rulers of the Kanto region. During this period, Nakajima Castle is thought to have been positioned as an important eastern base within the Later Hojo clan’s sphere of influence. Choshi’s geographical location, controlling the Tone River’s water transport and facing the Pacific Ocean, held significant military and economic value.
Fall of Nakajima Castle in 1590
In 1590, when Toyotomi Hideyoshi launched his siege of Odawara, the Kaijo clan, who had been loyal to the Later Hojo clan, shared the same fate. After Odawara Castle fell and the Hojo clan was destroyed, Nakajima Castle was abandoned by the Tokugawa forces in the Kanto region, which had come under the control of Tokugawa Ieyasu. At this time, the Kaijo clan’s power also came to an end, bringing to a close the approximately 400-year history of Nakajima Castle.
Layout and Structure of Nakajima Castle
Location and Utilization of Topography
Nakajima Castle is a flatland castle built on the eastern edge of a plateau facing the Tone River. Its location, cleverly utilizing the natural fortifications of the plateau, is a distinctive feature, providing defensive capabilities befitting a medieval Choshi stronghold. The castle grounds extend approximately 500 meters east-west and 400 meters north-south, making it one of the largest castles in the prefecture.
At the foot of the plateau, scattered houses remain, bearing the legend of having once been the residences of the castle lord’s retainers, preserving the memory of a castle town. This arrangement of remains suggests that Nakajima Castle functioned not merely as a military facility, but as a center of regional control.
Arrangement of Enclosures
Multiple enclosures were formed on the plateau using dry moats. Currently, about four large enclosures can be identified, each forming a defensive line and constituting the castle grounds. The main enclosure is at the center, with the second and third enclosures arranged in stages, creating a layout designed to gradually prevent enemy incursions.
While much of the enclosure area is now used as farmland, such as cabbage fields, the undulations of the terrain allow us to imagine what it looked like in the past. The combination of flat and sloping surfaces on the plateau creates a landscape characteristic of medieval castles.
Characteristics of Defensive Structures
The earthworks and dry moats are particularly noteworthy defensive structures of Nakajima Castle. Earthen ramparts were built surrounding the baileys, and while their height varied, some sections still maintain a height of several meters. These ramparts not only prevented enemy intrusion but also served to conceal the interior of the baileys.
Dry moats were important defensive structures separating the baileys, and their depth and width varied depending on the location. The moat protecting the main bailey was particularly large, reflecting the high level of defensive awareness at the time. Furthermore, smaller baileys called “koshi-kuruma” were built on the slopes of the plateau, indicating the adoption of a multi-layered defensive structure.
Highlights and Remains of Nakajima Castle
Kotohira Shrine (Konpira Shrine)
Currently, Kotohira Shrine (also known as Konpira Shrine) stands on the site of Nakajima Castle. This shrine is a symbolic landmark of the castle ruins and is the first place many visitors head to. Well-preserved castle remains are found within the shrine grounds, allowing visitors to enjoy viewing the ruins while paying their respects.
The path leading to the shrine is thought to be a remnant of the former castle’s access route. Imagining the samurai warriors who walked this path as you climb the stone steps is one of the joys of visiting castle ruins.
Preservation of the Earthworks
The earthworks of Nakajima Castle are among the best-preserved of medieval castles in the prefecture. The earthworks around Kotohira Shrine, in particular, remain clearly visible, allowing visitors to appreciate the castle’s original scale from its height and width. Walking along the top of the earthworks allows you to experience the castle’s defensive lines.
Observing the cross-section of the earthworks reveals that they were carefully constructed using a technique called rammed earth (hanchiku). This technique, which involves layering and compacting soil, was widely used in medieval castle construction.
The Impressive Dry Moat
The dry moat of Nakajima Castle captivates visitors with its size and excellent state of preservation. The moats, especially around the main enclosure, are deep, and looking up from the bottom to the top of the earthworks gives a real sense of their high defensive capabilities. There are even places where you can walk along the bottom of the moats, offering a valuable opportunity to experience the castle’s three-dimensional structure.
The dry moats are of the box-moat type, characterized by their flat bottoms. This is a common style found in medieval castles in the Kanto region, and is one piece of evidence indicating that Nakajima Castle belonged to the Kanto castle cultural sphere.
Terrain of the Enclosures
The flat surfaces of each enclosure remain clearly visible today, allowing us to imagine the layout of the buildings in the past. The main enclosure has the largest flat surface, and it is believed that the lord’s residence and important facilities were located here. The terrain, which gradually slopes down to the second and third enclosures, exhibits a typical structure of a medieval castle.
Earthworks surround the edges of the enclosures, creating a clear difference in elevation between the inside and outside. This structure allows for views from inside the enclosure to the outside, while making it difficult to see inside from the outside, resulting in an excellent design for both defense and surveillance.
Designation and Preservation of Nakajima Castle
Nakajima Castle ruins are protected as a designated historical site of Choshi City. As a castle from the Sengoku period (medieval castle), it is one of the largest in Chiba Prefecture, and because the remains of the castle’s defensive structures, such as moats, earthworks, and outer baileys, are well-preserved, it is positioned as an important historical heritage site of the region.
Information boards have been installed by the Choshi City Board of Education, allowing visitors to learn about the castle’s history and structure on-site. Regular maintenance, such as grass cutting, is carried out to preserve the remains and improve the viewing environment.
Access and Visiting Information for Nakajima Castle
Location
Address: 2-223 Nakajima-cho, Choshi City, Chiba Prefecture (Kotohira Shrine)
Access by Public Transportation
From Choshi Station on the JR Sobu Main Line and Choshi Electric Railway, take a Chiba Kotsu bus for approximately 10 minutes, get off at the “Nakajima-cho” bus stop, and walk for approximately 5 minutes. If you take a taxi from Choshi Station, it will take about 10 minutes to arrive.
It is about a 20-minute walk from Kannon Station on the Choshi Electric Railway, making it possible to combine a visit with a trip on the Choshi Electric Railway.
Access by Car
It is about 40 minutes from the Sawara-Katori Interchange on the Higashi-Kanto Expressway via National Route 356. From Choshi city center, it is about 10 minutes via National Route 126.
There is a parking space for visitors at Kotohira Shrine, but it is not large, so caution is advised during busy times. Since the surrounding area is residential, please avoid street parking and be considerate of the neighbors.
Points to Note When Visiting
The remains of Nakajima Castle are distributed over a wide area, including the grounds of Kotohira Shrine. While visiting is generally free, please observe proper etiquette for visiting shrines and refrain from trespassing on private property.
Since part of the castle ruins is used as farmland, care must be taken to avoid damaging crops. Also, some areas of the earthworks and moat slopes can be slippery, so comfortable walking shoes are recommended.
Estimated Visiting Time
If you plan to visit the main remains around Kotohira Shrine, 30 minutes to 1 hour is a good estimate. If you want to thoroughly explore the entire castle grounds and visit each enclosure, allow 1.5 to 2 hours. If you plan to take photographs or sketch the remains, it is recommended to allow even more time.
Combination Plans with Nearby Tourist Spots
Other Castle Ruins in Choshi City
Besides Nakajima Castle, there are several other medieval castle ruins scattered throughout Choshi City. These include Honjo Castle, Miyake Castle, Miyahara Castle, Moromochi Castle, Yagi Castle, and Shinobu Castle, allowing you to trace the castle network of the Kaijo clan and related forces. If you have time, you can enjoy a “Choshi Castle Tour” visiting these castle ruins.
Choshi Tourist Attractions
To combine a visit to Nakajima Castle with other sightseeing spots in Choshi, consider Inubosaki Lighthouse, Byobugaura, Choshi Port Tower, and the Choshi Electric Railway. Inubosaki, in particular, is about a 15-minute drive from Nakajima Castle and offers stunning views of the Pacific Ocean.
At Choshi Fishing Port, you can enjoy fresh seafood, making it a perfect meal after exploring the castle ruins. Choshi is also known as a soy sauce town, and factory tours of Yamasa Soy Sauce and Higeta Soy Sauce are popular.
Other Castles in Chiba Prefecture
For those interested in medieval castles in Chiba Prefecture, we recommend visiting Hon-Sakura Castle (Shisui Town), Sakura Castle (Sakura City), Otaki Castle (Otaki Town), and Moriyama Castle (Katori City). Comparing Nakajima Castle to these castles will provide a clearer understanding of its unique characteristics and significance.
Reference Materials for Learning About Nakajima Castle
For those who wish to learn more about Nakajima Castle, here are some reference materials.
Books and Documents
- *History of Chiba Prefecture* (Yamakawa Publishing): Mentions the Kaijo clan and Nakajima Castle within the context of Chiba Prefecture’s medieval history.
- *Comprehensive Guide to Japanese Castles*, Volume 6 (Shin Jinbutsu Oraisha): Nakajima Castle is listed as a castle in Chiba Prefecture.
- *A Tour of Ancient Castle Sites in Boso* (Ronshobo Publishing): Introduces castles in Boso, including Nakajima Castle.
- *Choshi City History*: Includes detailed records of Nakajima Castle as a local historical document.
Websites
Castle information websites such as Kojodan, Jōkaku Hōrōki, and Shirobito feature photos and impressions from actual visitors, which are useful for gathering information before visiting. The official Choshi City website also features Nakajima Castle ruins as cultural property information.
The Charm and Significance of Visiting Nakajima Castle
Nakajima Castle may lack a grand keep or stone walls, but it is a valuable historical site where you can experience the essence of a medieval castle. Its great value lies in the castle’s structure, built of earth and wood, its clever use of the terrain, and the fact that its defensive system from over 400 years ago still remains.
In recent years, with the growing interest in medieval castles, attention is also being drawn to regional castle ruins like Nakajima Castle. The quiet atmosphere, different from that of famous castles, allows for careful observation of the remains and the enjoyment of imagining its former glory, making it an invaluable experience for castle enthusiasts.
Best Season to Visit Nakajima Castle
Nakajima Castle ruins are open year-round, but each season offers a different charm.
Spring (March-May): The season of fresh greenery makes it easy to observe the topography of the earthworks and moats. The weather is mild and ideal for a stroll.
Summer (June-August): Due to overgrown vegetation, the ruins may be somewhat difficult to see. Please take sufficient precautions against heatstroke.
Autumn (September-November): The weather is stable, making it the ideal season for visiting castle ruins. The surrounding scenery is also beautiful during the autumn foliage season.
Winter (December-February): With the vegetation withered, this is the season when the shape of the ruins is easiest to observe. However, on windy days, warm clothing is necessary.
Summary
Nakajima Castle in Choshi City, Chiba Prefecture, is a historically significant site, being one of the largest medieval castles in the prefecture, built by the Kaijo clan. Constructed during the Kenkyu era, it functioned as the political and military center of the Choshi region for approximately 400 years until its abandonment in 1590, following the fall of the Hojo clan.
The well-preserved remains of the castle, including earthworks, dry moats, and baileys, are invaluable resources for learning about the structure of medieval castles. The castle ruins, now protected as part of the grounds of Kotohira Shrine, offer a tranquil environment where one can imagine its former glory.
Nakajima Castle, located near Choshi city center and relatively easy to access, is an essential spot for any castle tour in Chiba Prefecture. Be sure to visit it in conjunction with sightseeing in Choshi. Standing on the site of the castle built and defended by medieval samurai, you’ll feel the romance of history.
