Shiraiwa Castle (Akita Prefecture, Semboku City) Complete Guide | History and Highlights of the Thirty-Five Castles of Tozawa
Located in Semboku City, Akita Prefecture, Shiraiwa Castle is a mountain castle known as the residence of the Shiraiwa clan, who were active in Dewa Province during the Sengoku period. Built about 15 minutes east of Kakunodate, the “Little Kyoto of Michinoku,” on the east bank of the Tamagawa River at the foot of the Ou Mountains, this castle played a crucial role in the history of the Semboku region as a senior retainer of the Tozawa clan. This article provides a detailed explanation of Shiraiwa Castle, from its historical background to existing remains and highlights for visitors, aimed at castle enthusiasts and history buffs.
History of Shiraiwa Castle and the Lineage of the Shiraiwa Clan
Establishment of the Shiraiwa Clan and Construction of the Castle
The history of Shiraiwa Castle is closely related to the activities of the “Shiraiwa clan,” who took their surname from the Shiraiwa area from the Nanboku-cho period to the Sengoku period. The Shiraiwa clan established their power in this area as senior retainers of the Tozawa clan, who ruled the Semboku region of Dewa Province.
Shiraiwa Castle, also known as Tateyama, functioned as a mountain castle during the Sengoku period. The castle’s lords are known to be Shiraiwa Hyogo-no-kami Morishige and his son, Morinori. They held a senior position within the Tozawa clan and played a crucial role in the clan’s military activities.
Battles of the Tensho Period and the Activities of the Shiraiwa Clan
Important events in the Shiraiwa clan’s military activities that are recorded include the “Battle of Akino” in 1586 and the “Battle of Karamatsu” in 1587. In these battles, Shiraiwa Hyogo-no-kami Morishige and his son Morinori participated as the main force of the Tozawa clan, contributing to the maintenance of the Tozawa clan’s power in the Senboku region.
At that time in Dewa Province, fierce territorial disputes were raging between the Tozawa clan and surrounding daimyo, and Shiraiwa Castle functioned as one of the frontline strongholds.
Abandonment of Shiraiwa Castle under the Toyotomi Regime
The history of Shiraiwa Castle came to an end in 1590 (Tensho 18). As part of Toyotomi Hideyoshi’s pacification of Oshu, the “Tozawa Thirty-Five Castles,” which had been under the control of the Tozawa clan, were ordered to be abolished. Shiraiwa Castle was also abandoned as a result of this policy, ending its role as a mountain castle of the Sengoku period.
After its abandonment, a castle-like structure called a “hirajiro” (flatland castle) was built on the Shiraiwa site in the early Edo period, but this was a facility with a different character from the mountain castles of the Sengoku period.
Castle Structure and Remains of Shiraiwa Castle
Castle Location and Layout
Shiraiwa Castle is a mountain castle located on the east bank of the Tamagawa River, at the foot of the Ou Mountains. It has the typical structure of a medieval mountain castle, with the main keep at the summit called Tateyama, surrounded by multiple baileys. The layout, which skillfully utilizes the terrain, demonstrates the Sengoku period castle-building techniques that emphasized defense.
The castle’s location was a strategic point overlooking the Tamagawa River basin, making it strategically important for monitoring and controlling key transportation hubs in the Senboku region.
Details of Existing Remains
The current Shiraiwa Castle site retains well-preserved remains from the time of its construction. The main remains are as follows:
Earthworks
Earthworks, built as defensive structures for the castle, remain around each enclosure. These earthworks, constructed by piling up earth, prevented enemy intrusion and clearly defined the boundaries of the enclosures.
Moats
Moats dug to cut across the mountain ridges are a core feature of Shiraiwa Castle’s defensive system. They hindered enemy advances and strengthened the castle’s defenses. Multiple moats can be seen at the site.
Enclosure Remains
Multiple enclosures (flat areas) are arranged in terraces around the main enclosure. These enclosures are thought to have been used as garrisons for soldiers and storage areas for supplies.
Kojō Shrine and Faith
The Kojō Shrine is currently enshrined on the site of the main keep. It is an important historical site indicating that the castle ruins were used as a place of worship for the local community after the castle was abandoned. This shrine is carefully preserved by local residents and plays a role in passing on the history of Shiraiwa Castle to future generations.
History and Culture of the Shiraiwa Area
Shiraiwa as a Castle Town
A castle town was formed in the area surrounding Shiraiwa Castle from the Sengoku period to the early Edo period. The Shiraiwa area, designated as a historical site by Senboku City, retains several historical legacies, including Tateyama (a castle site from the Sengoku period) and Hirajo (a castle site from the early Edo period).
Unganji Temple and Temples and Shrines of Shiraiwa
In the Shiraiwa area is Unganji Temple, established in 1450 (Hōtoku 2). As a temple with a history older than Shiraiwa Castle, it has served as a spiritual pillar for the community. Unganji Temple likely also functioned as the family temple of the Shiraiwa clan, and the relationship between the castle and the temple is important for understanding medieval regional society.
Shiraiwa Sasara and Folk Culture
The Shiraiwa region is home to the traditional performing art “Shiraiwa Sasara,” designated as an important intangible folk cultural property of Akita Prefecture. This folk art is a valuable intangible cultural asset that conveys the history and culture of Shiraiwa to the present day, and it tells the story of the cultural richness of the era when it flourished as a castle town.
Shiraiwa Castle Visiting Guide
Highlights of the Castle Site
When visiting Shiraiwa Castle, paying attention to the following points will allow you to understand the castle’s history more deeply.
Main Keep Site and Kojō Shrine
The Kojō Shrine is enshrined at the main keep site, which is located at the highest elevation. From here, you can enjoy a panoramic view of the Shiraiwa region and the Tamagawa River basin, allowing you to appreciate the importance of the castle’s location.
Scale of the Moat
The moat, cutting across the mountain ridge, is the most impressive surviving structure demonstrating the defensive capabilities of Shiraiwa Castle. Observing its depth and width allows one to understand the level of castle construction technology during the Sengoku period.
Arrangement of Earthworks
Observing the arrangement of earthworks surrounding each enclosure allows one to appreciate the skillful layout of the castle.
Nearby Historical Spots
When visiting Shiraiwa Castle, we recommend also visiting the nearby historical spots.
Kakunodate Samurai Residence Street
Kakunodate, known as the “Little Kyoto of Michinoku,” is about a 15-minute drive from Shiraiwa Castle. The samurai residence street, designated as an Important Preservation District for Groups of Traditional Buildings, allows you to experience the samurai culture of the Edo period.
Hirajo Castle Site
This is the site of an early Edo period castle located within the Shiraiwa area, and is an important historical site for understanding the history after the abandonment of Shiraiwa Castle.
Unganji Temple
A historic temple established in 1450, it is the spiritual and cultural center of the Shiraiwa region.
Access
Access by Car
From Akita City
- Approximately 50 minutes from the Omagari IC on the Akita Expressway via National Route 105
- Approximately 15 minutes from Kakunodate town center via the prefectural road
From Morioka
- Approximately 1 hour 30 minutes from the Morioka IC on the Tohoku Expressway via National Route 46
Parking is limited to the area around the castle ruins, so it is recommended to check in advance.
Access by Public Transportation
Train
- Get off at Kakunodate Station on the JR Akita Shinkansen/Tazawako Line
- Approximately 20 minutes by taxi from Kakunodate Station
Bus
Buses from Kakunodate Station to Shiraiwa are limited, so please check the timetable in advance.
Points to Note When Visiting
- As it is a mountain castle, comfortable shoes and clothing are recommended.
- Insect repellent is necessary during the summer.
- Visiting may be difficult during the winter due to snow.
- Please follow the designated viewing route to protect the remains.
Shiraiwa Castle and the Thirty-Five Castles of Tozawa
The Tozawa Clan’s Territory
Shiraiwa Castle, as one of the “Thirty-Five Castles of Tozawa,” played an important role in the Tozawa clan’s system of rule. The Tozawa clan controlled a vast territory centered on the Senboku region, and managed their domain by placing branch castles throughout the area.
The Thirty-Five Castles of Tozawa is a collective term for the castles that were directly controlled by the Tozawa clan or governed by local lords under their control. These castles were interconnected, forming the Tozawa clan’s military and administrative network.
The Role of the Shiraiwa Clan
As a senior retainer of the Tozawa clan, the Shiraiwa clan was not merely the lord of a branch castle, but held a position of senior advisor to the Tozawa clan. This is evident from the fact that Shiraiwa Hyogo-no-kami Morishige and his son, Morinao, participated in major battles.
Shiraiwa Castle is thought to have functioned not only as a military base but also as the administrative and economic center of the Tamagawa River basin.
Historical Value of Shiraiwa Castle
Significance as a Semboku City Designated Historic Site
Shiraiwa Castle (Tateyama) is designated as a Semboku City Historic Site and is positioned as an important cultural property of the region. As a well-preserved structure of a Sengoku period mountain castle, it has high academic value.
Importance in Local History
The history of Shiraiwa Castle is an indispensable element in understanding the political and military situation in the Sengoku period in the Semboku region of Dewa Province. As a concrete example showing the expansion and decline of the Tozawa clan’s power and the process of Toyotomi regime’s control over Tohoku, it occupies an important position in the study of Japanese medieval history.
Symbol of Regional Identity
For the Shiraiwa region, Shiraiwa Castle is a symbol of the region’s history and culture. The history of Shiraiwa Castle, which flourished as a castle town of the Shiraiwa clan, forms the foundation of the current Shiraiwa region’s identity and is carefully preserved and passed down by local residents.
Current Status and Challenges of Shiraiwa Castle Research
Archaeological Excavations and Research
Regarding Shiraiwa Castle, full-scale archaeological excavations have been limited to date, and research has mainly focused on the analysis of historical documents and existing remains. If planned investigations are conducted in the future, more detailed information about the castle’s structure and period of use may be obtained.
Efforts for Preservation and Utilization
Senboku City is working on the preservation and utilization of the region’s historical heritage, including Shiraiwa Castle. The challenge going forward is to maintain the state of preservation of the remains while promoting their use in historical education and as a tourist resource.
Summary
Shiraiwa Castle is a valuable Sengoku period mountain castle ruin remaining in Senboku City, Akita Prefecture. As the residence of the Shiraiwa clan, important retainers of the Tozawa clan, it participated in battles during the Tensho period, leaving an important mark on the history of the Senboku region. Although its role ended with Toyotomi Hideyoshi’s decree to abolish castles in 1590, the remains of earthworks and moats are still well-preserved, and the Kojō Shrine is located on the site of the main keep.
Located near Kakunodate, known as the “Little Kyoto of Michinoku,” the Shiraiwa area is rich in history and culture, including Unganji Temple and Shiraiwa Sasara. For those interested in the history of Dewa Province during the Sengoku period, and for castle enthusiasts, Shiraiwa Castle is a historical site well worth visiting. Combine your visit with sightseeing in Kakunodate and experience the spirit of the Sengoku period.
Understanding the history of Shiraiwa Castle will lead to a deeper understanding of Akita Prefecture’s medieval history and Japan’s Sengoku period. It is important to continue to carefully preserve this historical heritage rooted in the region and pass it on to future generations.
