Kashima Castle (Matsuyama City, Ehime Prefecture) | History and Remains of the Kono Navy’s Naval Castle in the Seto Inland Sea
What is Kashima Castle?
Kashima Castle is a naval castle built on Kashima Island, located approximately 300 meters offshore from the Hojo district of Matsuyama City, Ehime Prefecture. This island, designated as part of the Seto Inland Sea National Park, is a small island with a circumference of about 1.5 km, yet it functioned as an important maritime base for the Kono Navy during the medieval period.
Today, Kashima is a popular tourist destination with beaches, campgrounds, and walking trails. However, remnants of the castle, such as stone walls, still remain on the mountaintop and slopes, allowing visitors to imagine its former glory. As a naval castle of Iyo Province, Kashima Castle played a crucial role in monitoring and controlling maritime traffic in the Seto Inland Sea, making its history indispensable for understanding the medieval history of this region.
History of Kashima Castle
Construction Period and Builder
There are no clear records of when or by whom Kashima Castle was built. However, the “Iyo Kazahaya-shi,” a historical document preserved at the Aragami Shrine in Amasaki, Kamiura-cho, Ochi-gun, contains the history of the Kazahaya region along with the history of Amasaki Castle’s founding, providing clues to the establishment of Kashima Castle.
Generally, the prevailing theory is that the castle was built around the Kenmu era (1334-1338) by Imaoka Shiro Michitaka, who served as the jitō (land steward) of the Kazahaya region. This period coincided with the early Nanboku-chō period, a time of intense conflict among maritime powers in the Seto Inland Sea. It is believed that the castle was built on Kashima, a natural stronghold, to protect the Kazahaya sea area, a crucial point for maritime traffic, within Iyo Province, which was under the influence of the Kōno clan.
The Kono Navy and Kashima Castle
Kashima Castle was one of the maritime bases of the Kono Navy, which was active in the Seto Inland Sea during the medieval period. The Kono clan was a powerful samurai family in Iyo Province, and they expanded their power by controlling maritime traffic in the Seto Inland Sea. Because Kashima Castle is located offshore from Hojo Port, it is presumed to have played a role in monitoring the movement of ships from the Hiuchi Sea and intercepting or defending them as needed.
As a maritime castle, Kashima Castle had characteristics different from land-based castles. A defensive system that utilized the island’s topography, a structure designed for communication by ship, and visibility from the sea were all emphasized. It is thought that the castle was designed with naval warfare in mind, featuring inlets where the Kono Navy’s fleet could anchor and high vantage points for lookouts.
Kashima Castle in the Sengoku Period
During the Sengoku period (Warring States period), Kashima Castle became a stage for power struggles within Iyo Province. In particular, during the Tensho era (1573-1592), the area was affected by Toyotomi Hideyoshi’s conquest of Shikoku.
In 1585, Toyotomi Hideyoshi dispatched a large army aiming to unify Shikoku. When the forces, led by Kobayakawa Takakage, invaded Iyo Province, Kurushima Michifusa, a senior retainer of the Kono clan, played a crucial role as the vanguard. It is believed that Kashima Castle functioned as a strategically important base during this battle.
After the conquest of Shikoku, the Kono clan was destroyed, and Iyo Province came under the control of Kobayakawa Takakage. Subsequently, when the Kobayakawa clan was transferred to another domain, it is presumed that Kashima Castle gradually lost its military role. During the Edo period, it lost its function as a castle, and Kashima came to be used as a place of worship and a fishing base.
Kashima Castle’s Layout and Remains
Main Enclosure (Mountaintop)
The main enclosure of Kashima Castle is located on the mountaintop at an altitude of 114m. Currently, an observation deck has been installed at this location, offering a spectacular panoramic view of the Hiuchi Sea. From the main enclosure, a 360-degree view unfolds, allowing you to see not only the Hojo Port area but also the islands of the Seto Inland Sea and even Honshu.
To the south of the main enclosure is a distinctive rock called “Hatatate-iwa” (Flag-Raising Rock) with a hole in it. It is said that this rock was used to display the castle’s flag, and it is thought to have played a role in improving visibility from the sea. While no clear remains such as earthworks or moats have been confirmed in the main enclosure area, it is clear that the layout made the most of the mountaintop terrain.
Second Enclosure (Mid-slope)
From the main enclosure, several small terraced enclosures continue northeastward, and beyond that, on the northeastern slope of the mountain, is a large enclosure called “Ninodan” (Second Enclosure). The stone walls of the castle site remain in excellent condition on this second level, making it a valuable historical site of Kashima Castle.
The stone walls are constructed using the nozura-zumi technique, characteristic of medieval castles. The presence of stone walls on the south side of the second level suggests that this enclosure was not merely a lower enclosure, but an important section with a certain defensive function. It was likely used as a soldiers’ garrison or a storage area for supplies.
Other Remains
Stone walls have also been confirmed on the southwest side of the main enclosure, indicating a structure that allowed for defense from multiple directions. However, large-scale moats, earthworks, and stone walls, typical of land-based mountain castles, are not found. This is likely because, given its nature as a coastal castle, the island’s topography itself served as a natural moat.
Walking along the walking path, flat areas and elevation changes can be seen in places; these may also be the remains of enclosures or pathways. However, many parts have been altered due to use since the Edo period and modern tourism development, making it difficult to definitively identify all areas as pure castle remains. ## Kashima Shrine and the Faith of Kashima
Kashima Island is home to the Kashima Shrine, which has ties to the Kono naval force. It is said that the shrine was founded by the Kono clan to pray for safety at sea and victory in battle, and it continues to be a place of worship for the local community.
At Kashima Shrine, a traditional event called “Kaineri” is held during the spring and autumn festivals. Kaineri is a dance using boat oars, and is considered a remnant of the Kono naval force’s training and prayers for victory. This event is a valuable intangible cultural asset that conveys the history of Kashima Castle and the Kono naval force, and is carefully preserved by the local people.
The island also features Futami-iwa, a large rock adorned with a large sacred rope, and has the character of a place of worship for praying for safety at sea. It tells the story of how Kashima Castle, a military base, transformed into an island of faith over time.
Access and Visiting Information for Kashima Island
Access Method
To reach Kashima Island, take a ferry from Hojo Port. From central Matsuyama City to Hojo Port, it’s approximately a 30-minute drive. If using public transport, take the Iyo Railway Hojo Line to Hojo Station, then it’s about a 15-minute walk.
The ferry from Hojo Port to Kashima Island takes only about 3 minutes and is characterized by its deer-shaped finials. Ferry fares and operating times vary seasonally, so it’s recommended to check the Matsuyama City official website in advance.
Facilities and Visiting Information on the Island
Kashima Island has facilities such as a swimming beach, campground, barbecue area, inn, and shops, attracting many tourists, especially during the summer. In winter, it’s popular with anglers.
To visit the remains of Kashima Castle, use the island’s walking trails. The trails are well-maintained along the shore and up to the mountaintop, making it relatively easy to reach the mountaintop observation deck. However, since visiting the remains such as the stone walls requires entering the mountain, it is important to prepare appropriate clothing and shoes.
The time required to reach the summit is approximately 20-30 minutes one way at a leisurely pace. Climbing while viewing the stone walls of the second section along the way will allow you to gain a deeper understanding of the structure of Kashima Castle.
Precautions for Visiting
The remains of Kashima Castle are not protected by fences or other barriers, but remain in a natural environment. When viewing the remains such as the stone walls, be careful not to get too close due to the risk of collapse. Also, damaging the remains or taking stones is strictly prohibited.
In summer, there are many mosquitoes and insects, so insect repellent is necessary. Drinking water can be purchased at the island’s shops, but it is recommended to prepare some before climbing.
Historical Value of Kashima Castle
Characteristics as a Coastal Castle
Kashima Castle is a valuable example of a coastal castle in the history of Japanese castles. The Seto Inland Sea is home to numerous islands, and in the Middle Ages, many coastal castles were built on these islands. However, only a limited number of these castles remain today. The stone walls and bailey remains of Kashima Castle are important resources for understanding the structure of coastal castles.
Coastal castles were built based on a different design philosophy than land-based mountain castles or flatland castles. They required functions specifically tailored to the maritime environment, such as monitoring maritime traffic, securing anchorages for fleets, and defending against attacks from the sea. The location and layout of Kashima Castle reveal these unique features of coastal castles.
The History of the Kono Clan and the Seto Inland Sea
The history of Kashima Castle is closely intertwined with the history of the Kono clan, a powerful samurai family of Iyo Province during the Middle Ages. The Kono clan expanded their power by controlling maritime traffic in the Seto Inland Sea and led a naval force that was active in various regions. Kashima Castle played an important role in the medieval history of the Seto Inland Sea as one of the bases of the Kono naval force.
The fall of the Kono clan during the conquest of Shikoku drastically altered the balance of power in the Seto Inland Sea. Kashima Castle also experienced this historical turning point, transforming from a military base to a place of worship and daily life. This transformation symbolizes the transition period from the medieval to the early modern era in Japan.
Significance in Local History
Kashima Castle is an indispensable part of the history of the Hojo district of Matsuyama City, and by extension, the Kazahaya region. Local people continue to pass on the memory of the Kono naval force and Kashima Castle through traditional events such as the spring and autumn oar-carrying festival.
Kashima, designated as part of the Seto Inland Sea National Park, is protected not only for its beautiful natural scenery but also for its historical value. Balancing tourist development with the preservation of historical heritage remains a challenge for the future.
Related Historical Sites in the Surrounding Area
Castles in the Kazahaya Region
Other castles built in the Kazahaya region also exist around Kashima Castle. These castles are thought to have functioned in coordination with each other within the Kono clan’s system of rule. When visiting Kashima Castle, visiting these related historical sites in conjunction will allow for a deeper understanding of the region’s medieval history.
Relationship with Matsuyama Castle
Matsuyama Castle, a representative castle of Matsuyama City, is a modern castle built in the early Edo period by Kato Yoshiaki. While different in era and character from Kashima Castle, as a castle within Matsuyama City, it serves as a good example of the diversity of Japanese castle history.
Matsuyama Castle is a famous castle visited by many tourists as a flatland castle with an existing keep. On the other hand, Kashima Castle is a coastal castle with limited remains, but its historical value is by no means inferior. By comparing the two, one can learn about the diverse forms and roles of castles.
The Present and Future of Kashima Castle
Utilization as a Tourism Resource
Present-day Kashima is a tourist destination where visitors can enjoy leisure activities such as swimming, camping, and fishing, as part of the Seto Inland Sea National Park. The island is home to real deer roaming freely, and visitors are greeted by deer upon disembarking from the ferry, making it a popular and approachable tourist spot.
While the remains of Kashima Castle are positioned as one of these tourist resources, they are not yet being fully utilized. Although the view from the mountaintop observation deck is magnificent, there is currently insufficient information provided regarding the value of the castle ruins and their historical background.
Preservation and Education of Historical Heritage
The remains of Kashima Castle, such as its stone walls, are at risk of being lost due to natural weathering and human damage if appropriate preservation measures are not taken. It is desirable to conduct detailed surveys and academic research to clarify the value of the remains and to formulate a preservation plan.
Furthermore, it is important to incorporate the history of Kashima Castle into local school education and lifelong learning programs. If local children can learn about the history of Kashima Castle and develop a sense of pride, it will contribute to nurturing future leaders in preservation activities.
Future Prospects
Kashima Castle is a historical site with the potential to balance tourism and the preservation of historical heritage. For example, installing explanatory signs along the walking paths to explain the location and significance of the castle remains, or utilizing technologies such as VR and AR to recreate the castle’s appearance in its heyday, could provide visitors with a deeper historical experience.
Holding events in conjunction with traditional ceremonies such as oar-carrying rituals, and planning historical tours themed around the Kono naval force, would also be effective means of widely communicating the value of Kashima Castle. It is hoped that local residents, government officials, researchers, and tourism businesses will cooperate to pass on this valuable historical heritage of Kashima Castle to future generations.
Summary
Kashima Castle is a sea castle built on Kashima Island, located off the coast of Hojo, Matsuyama City, Ehime Prefecture. In the Middle Ages, it functioned as an important maritime base for the Kono naval force. It is believed to have been built by Imaoka Shiro Michitaka during the Kenmu era, and its military role ended with the fall of the Kono clan after the conquest of Shikoku during the Tensho era.
Even today, remnants such as stone walls remain on the main enclosure at the mountaintop and on the second level of the mountainside, providing valuable historical evidence of a coastal castle. Kashima is designated as part of the Seto Inland Sea National Park and is a popular tourist destination, but it also possesses significant historical value.
Despite being only about a 3-minute ferry ride from Hojo Port, Kashima is a place where rich nature and history coexist. Visiting the remains of Kashima Castle allows you to learn about the medieval history of the Seto Inland Sea, the activities of the Kono naval force, and the unique form of coastal castle. When visiting Matsuyama City, be sure to stop by Kashima and experience the great history etched into this small island.
