Tobari Castle (Kashiwa City, Chiba Prefecture) Complete Guide | History, Remains, and Access Information
Tobari Castle, located in Kashiwa City, Chiba Prefecture, was a hilltop castle that served as an important base for the Soma clan in Shimosa Province during the medieval period, playing a central role in regional control for approximately 200 years. Currently, it is difficult to visit as it is part of the grounds of Bunkyo Ward’s Kashiwa Gakuen school, but it is a castle site indispensable to understanding the history of the Chiba clan and attracts attention from castle researchers and history enthusiasts.
This article provides a comprehensive overview of Tobari Castle, including its detailed history, castle structure, the state of its remains, access methods, and related castles in the surrounding area.
Basic Information on Tobari Castle
Location and Geographical Characteristics
Location: 909, Shiroyamadai, Tobari, Kashiwa City, Chiba Prefecture (within Bunkyo Ward Kashiwa Gakuen)
Former Province: Katsushika District, Shimosa Province
Elevation: Approximately 20-25 meters
Location: On a tongue-shaped plateau on the southern shore of Lake Teganuma
Tobari Castle is located approximately 2 kilometers southeast of JR Kashiwa Station, and is skillfully built utilizing a long, narrow tongue-shaped plateau that juts out from southwest to northeast. The terrain overlooking Lake Teganuma offered both advantages for water transport and defensive capabilities, making it an ideal location for controlling this region during the medieval period.
Castle Classification and Structure
Classification: Hilltop Castle
Structure: Concentric Enclosures
Main Remains: Enclosures, Lower Enclosures, Earthworks, Dry Moats, V-shaped Moats, Enclosures
Keep Structure: Unknown (No keep existed as it is a medieval castle)
Tobari Castle is a typical medieval conceivable hilltop castle with multiple enclosures arranged east and west. It makes maximum use of the tongue-shaped plateau terrain, employing a design philosophy that utilizes natural elevation differences as defensive lines.
Castle Construction and Lords
Builder: Tobari Yukitsune (legend)
Year of Construction: Early Kamakura period (estimated early 13th century)
Main Lords: Tobari clan, Tatezawa clan (various theories exist)
Common Name/Alternate Name: Tobari Castle Mountain
History of Tobari Castle
Origins and Establishment of the Tobari Clan
To understand the history of Tobari Castle, it is necessary to first understand the origins of the Tobari clan. The Tobari clan was a branch of the Kanmu Taira clan’s Chiba clan, and belonged to the lineage of the Soma clan, whose founder was Soma Moritsune, the sixth son of Chiba Tsunetane.
It is said that the clan began when Tobari Hachiro Yukitsune, the third son of Soma Moritsune, ruled the Tobari area in Katsushika District, Shimosa Province, and adopted the name Tobari. In the early Kamakura period, Chiba Tsunetane, who followed Minamoto no Yoritomo’s uprising, earned the respect of his descendants, who acquired territories throughout Shimosa Province and established branch families. The Tobari clan was one such family, establishing roots in this area.
The Tobari Clan from the Kamakura to Muromachi Periods
The Tobari clan is said to have been based in this area for approximately 200 years, from the Kamakura to the Muromachi periods. As a branch of the Chiba clan, they played a key role in the Chiba clan’s power in northern Shimosa Province, solidifying their control over the area around Lake Teganuma.
Even after the main branch of the Soma clan moved to Oshu Soma (present-day Fukushima Prefecture), the Tobari clan remained in Shimosa, continuing to exist as influential local lords. It is believed they fulfilled diverse roles as medieval lords, including managing agricultural production, controlling water transport, and engaging in diplomacy with surrounding regions.
The Tatezawa Clan as Castle Lord and Other Theories
On the other hand, there is also a theory that the Tatezawa clan was the lord of Tobari Castle. The Tatezawa clan is also considered a branch of the Chiba clan and may have held influence in this region.
Due to the limited historical records concerning the castle’s lords, many details remain unclear, such as the relationship between the Tobari and Tatezawa clans, or the changes in castle lords over time. This is a common challenge for castles of medieval local powerful families and is an area where further research is needed.
The Sengoku Period and the End of the Castle
With the arrival of the Sengoku period, Shimosa Province became a fierce battleground with various clans such as the Hojo, Satomi, and Satake. The Chiba clan gradually came under the influence of the Hojo clan, and when the Hojo clan was destroyed in Toyotomi Hideyoshi’s Odawara campaign in 1590, the Chiba clan also declined.
It is unclear when Tobari Castle was abandoned, but it is thought to have lost its function as a military base around this time. From the Edo period onward, the land was used for agriculture, and the castle remains gradually disappeared.
Layout and Remains of Tobari Castle
Overall Layout
Tobari Castle is situated on a long, narrow, tongue-shaped plateau, with a linear layout centered around two baileys, one on the east and one on the west. It is presumed that the main bailey was located at the tip of the plateau (east side), with the second and third baileys continuing towards the west.
A lower bailey was positioned along the side of the plateau, suggesting a design intended to allow flanking fire against enemies climbing the slope. Furthermore, a moat was likely constructed at the base of the plateau to prevent incursions from the rear.
Structure of the Baileys (Enclosures)
Multiple baileys have been identified at the castle site, each demarcated by earthen ramparts. The eastern bailey, presumed to be the main bailey, is located at the highest point of the plateau and was surrounded by earthen ramparts.
The size of the baileys is standard for a medieval local lord’s castle, combining residential and defensive functions. It is thought to have functioned as the lord’s living space in peacetime and as a defensive base during wartime. ### Characteristics of the Earthworks
The earthworks of Tobari Castle were constructed to surround the baileys, and parts of them remain well-preserved today. They are approximately 1-2 meters high, a typical size for medieval castles.
The earthworks served not only as defensive walls but also as a symbolic element, dividing the space within the baileys and demonstrating authority. It is possible that fences or walls were built on top of the earthworks.
Dry Moats and Horizontal Moats
A notable feature of Tobari Castle’s defensive structures is the presence of dry moats and horizontal moats. Horizontal moats were dug along the side of the plateau, designed to hinder enemy lateral movement.
Furthermore, some sections have been identified as Yagen-bori, moats with a V-shaped cross-section. Yagen-bori are difficult to climb and offer high defensive capabilities. These moats are a common feature of castles built by the Chiba clan, indicating that Tobari Castle was constructed using Chiba clan-style castle-building techniques.
Koguchi (Entrance)
The koguchi, the entrance to a castle, is the most important defensive structure. At Tobari Castle, multiple locations believed to be koguchi have been identified, showcasing defensive structures combining earthworks and moats.
Koguchi were not simple openings; they were designed with curves and square shapes to make enemy intrusion difficult.
Bunkyo City Kashiwa Gakuen and Current Status
Establishment of Kashiwa Gakuen and Use of Castle Sites
The Tobari Castle site became the site of Bunkyo City Kashiwa Gakuen, established by Bunkyo Ward, Tokyo, during the Showa era. Kashiwa Gakuen was used as a forest school facility for Bunkyo Ward elementary schools, and many children have participated in nature-based learning experiences here.
While some parts of the castle site were altered due to the construction of the school facilities, major remains such as earthworks and moats have been preserved relatively well. Information boards explaining the remains have also been installed on the site.
Closure and Restrictions on Access in 2013
In 2013 (Heisei 25), Kashiwa Gakuen was closed due to a policy change by Bunkyo Ward. Consequently, access to the castle ruins was prohibited, and the main gate remains closed to this day.
Since the closure, site management has been limited, making it difficult for castle enthusiasts and researchers to view the remains. Only a portion of the earthworks can be seen from outside the gate; detailed investigation and photography are virtually impossible.
Challenges of Preservation and Utilization
The closure of Kashiwa Gakuen has created new challenges regarding the preservation and utilization of the Tobari Castle ruins. To pass on these valuable medieval castle remains to future generations, appropriate preservation management and, if possible, consideration of public access are desirable.
Discussions with the Kashiwa City Board of Education and Bunkyo Ward are expected to lead to initiatives that leverage the value of the remains, such as designation as a historical site and the holding of limited guided tours.
Access and Visiting Information
Access by Public Transportation
Nearest Station: JR Joban Line/Tobu Noda Line “Kashiwa Station”
Distance: Approximately 2 kilometers southeast from Kashiwa Station
Bus: Take a Tobu Bus bound for “Tobari” or “Kashiwa Gakuen” from the east exit of Kashiwa Station, and get off at the “Kashiwa Gakuen” bus stop.
While it’s possible to walk from Kashiwa Station in about 30 minutes, using the bus is more convenient. However, currently, entry to the grounds is not permitted, so only exterior viewing is possible.
Access by Car
Joban Expressway: Approximately 15 minutes from Kashiwa IC
Parking: None (Street parking is strictly prohibited as it will inconvenience the neighborhood)
When visiting, please avoid street parking and use public transportation to avoid inconveniencing local residents.
Notes for Visitors
- No Entry: Currently, entry to the Kashiwa Gakuen grounds is prohibited.
- Exterior Viewing Only: Please limit your visit to viewing the exterior from near the main gate.
- Consideration for Private Property: The surrounding area is a residential area, so please be mindful of noise and trespassing.
- Photography: Photography is permitted from the public road, but please be considerate of the privacy of residents on the grounds and in the surrounding area.
Related Castles in the Surrounding Area
To gain a deeper understanding of the historical background of Tobari Castle, we recommend visiting the related castles in the surrounding area as well.
Masuo Castle (Masuo, Kashiwa City)
Located approximately 3 kilometers north of Tobari Castle, Masuo Castle was also a castle of the Chiba clan. The remains of the earthworks and moats are well-preserved and easily accessible for viewing. As a castle that functioned at the same time as Tobari Castle, it is a subject of comparative research.
Fuse Castle (Fuse, Kashiwa City)
Located on the north shore of Lake Teganuma, Fuse Castle is believed to have been the residence of the Takagi clan. Located across Lake Teganuma from Tobari Castle, its position is important for understanding the power dynamics of this region.
Fujishin Castle (Fujishin, Kashiwa City)
Fujishin Castle, located near the center of Kashiwa City, was also a castle of the Chiba clan and has a similar structure to Tobari Castle. The remains are scattered throughout a residential area, making it a good example of how castle ruins are preserved in urban areas.
Minowa Castle (Minowa, Kashiwa City)
Located east of Tobari Castle, Minowa Castle, though smaller in scale, retains clear remains. Its connection to Tobari Castle has been pointed out as part of a network of branch castles within the Chiba clan’s sphere of influence.
Historical Significance of Tobari Castle
Evidence of the Chiba Clan’s Power Expansion
Tobari Castle is an important archaeological site demonstrating the expansion of the Chiba clan’s power during the Kamakura period. Tobari Castle tells the story of how the descendants of Chiba Tsunetane dispersed throughout Shimosa Province, each establishing their own independent power base.
The fact that the Tobari clan, which branched off from the Soma clan, ruled this area for 200 years is a valuable example for understanding the establishment of local powerful families and the realities of regional control in the medieval period.
A Key Point on Lake Teganuma Water Transport
The location of Tobari Castle on the southern shore of Lake Teganuma is no mere coincidence. In the medieval period, Lake Teganuma was an important water transport route, used for the transportation of goods and military movements.
Tobari Castle is thought to have functioned as a base for controlling this water transport, playing a crucial role economically and militarily. It is a castle site of high research value as a good example illustrating the relationship between water transport and castles.
Resources for Medieval Castle Research
The layout and remains of Tobari Castle provide important resources for the study of medieval flatland castles. The castle exhibits characteristics typical of Chiba clan castles, such as its multi-bailey structure, the arrangement of earthworks and moats, and the design of its gate, making it a valuable research subject for castle researchers.
Although visits are currently difficult, past survey records and maps are still being used to elucidate the actual state of medieval castles.
Points to Note When Visiting Tobari Castle
Preparations
Please keep the following points in mind when visiting Tobari Castle.
- Confirmation of Restricted Access: Check the latest status with the Kashiwa City Board of Education, etc.
- Prepare a Map: Since it is located in a residential area, prepare a detailed map.
- Combination with Surrounding Castles: Plan in conjunction with other castle ruins that can be visited, such as Masuo Castle.
- Prior Study of Materials: Since the remains are difficult to see, understand the structure beforehand using a layout map, etc.
Best Season for Visiting
Since only exterior viewing is possible, there is no particular need to choose a season, but the winter months (November to March), when the leaves of the trees have fallen, may make it easier to see the topography such as earthworks.
Tips for Photography
- Part of the earthworks can sometimes be seen from near the main gate.
- A telephoto lens will allow you to capture details of the remains even from a distance.
- Please be considerate of the privacy of the surrounding residents.
Summary
Tobari Castle is a valuable medieval castle ruin remaining in Kashiwa City, Chiba Prefecture. The Tobari clan, a branch of the Soma clan, made this their base for approximately 200 years, and it played a central role in regional control as a strategic point on the southern shore of Lake Teganuma.
Currently, access is prohibited due to the closure of Bunkyo Ward Kashiwa Gakuen, but the remains such as earthworks, baileys, and dry moats are relatively well-preserved and hold significant value in the study of medieval castles.
Although visiting is difficult, Tobari Castle is indispensable for understanding the history of the Chiba clan and their regional control of Shimosa Province during the medieval period. Visiting it along with nearby castles such as Masuo Castle and Fuse Castle will allow you to grasp the overall picture of the medieval castle network in this region.
We hope that appropriate preservation, management, and utilization will progress in the future, and that many people will be able to experience this valuable historical heritage. We also hope that castle enthusiasts will observe proper etiquette during their visit and be mindful of passing on this valuable cultural asset to future generations.
