Although the modern city of Kaizu as an administrative unit appeared on the map of Japan in 2005 following the merger of the towns of Kaizu, Hirata, and Nanno, the history of settlement in this area dates back to ancient times. Archaeological data indicates a human presence in the region since prehistoric times. A key stage in the historical formation of the region was the Edo period (1603–1868), when these lands were the center of the Takasu Domain — an important feudal estate ruled by a branch of the Tokugawa clan.
Key Factors of Formation
The city's development was determined by the complex interaction between man and the water, which shaped the unique character of the area:
Geography of the Three Rivers: Kaizu is located in the lowest part of the Nobi Plain, at the confluence of three major rivers: the Kiso, Nagara, and Ibi. This position made the region important yet dangerous for habitation due to frequent flooding.
The "Waju" System: A defining factor for survival and urban planning was the construction of waju — ring levees surrounding settlements and fields. This specific structure turned local villages into a kind of fortress-island, protected from the water.
Political Influence: Proximity to the influential Owari Domain and its status as the residence of the daimyo at Takasu Castle contributed to political stability and the flow of resources into the region.
Early Cultural and Economic Features
The economy of early Kaizu was based on highly productive agriculture. Thanks to the fertile alluvial soils within the levees, rice cultivation flourished, although it was fraught with the risk of flooding. The rivers served as the main transport arteries, providing trade links with Osaka and Edo. The cultural identity of the residents was formed on the basis of strict discipline and mutual assistance, which were necessary for the joint maintenance of protective structures and water resource management.
Timeline
Key Milestones in Kaizu's History
1600s — Active development and strengthening of the unique "waju" system (settlements surrounded by levees) for protection against regular flooding in the river delta.
1700 — Establishment of the Takasu Domain, which became the residence of one of the influential branches of the ruling Tokugawa clan.
1754 — Commencement of large-scale work to regulate the Kiso, Nagara, and Ibi rivers (the Horeki Incident), carried out by Satsuma samurai at the cost of immense effort and sacrifice.
1871 — Abolition of the feudal domains and the inclusion of the Takasu Domain territory into modern-day Gifu Prefecture.
1897 — An administrative reform officially establishes the boundaries of the Kaizu District.
1954–1955 — Formation of the independent towns of Kaizu, Hirata, and Nanno during the municipal mergers of the Showa period.
1987 — Opening of the Kiso Sansen National Government Park, which became a symbol of the region and a popular recreation spot.
March 28, 2005 — Official foundation of the modern city of Kaizu through the merger of the towns of Kaizu, Hirata, and Nanno.
Milestones
Evolution and Key Transformations
The development of Kaizu is a story of a constant struggle for living space among rivers and the transformation of natural challenges into economic advantages. Below are the key stages that shaped the modern look and lifestyle of the city:
Creation and Strengthening of the "Waju" System Historically, residents built ring levees around their settlements. This not only defined the unique urban structure (houses on elevations surrounded by fields) but also formed a specific local mentality based on solidarity and mutual aid in the face of natural elements.
Separation of the Three Rivers (The Johannis de Rijke Project) During the Meiji era, under the guidance of Dutch engineer Johannis de Rijke, colossal work was carried out to separate the channels of the Kiso, Nagara, and Ibi rivers. This was a turning point in urban planning: the risk of catastrophic flooding decreased, allowing for the stabilization of land boundaries and infrastructure development.
Transition to Intensive Farming Thanks to improved irrigation and flood protection, the city's economy was transformed. Farmers moved from risky rice cultivation to high-tech greenhouse farming. Today, Kaizu is famous for its tomatoes and strawberries, which form the basis of the region's agricultural prosperity.
Development of Religious Tourism (Ochobo-san) The Chiyaho Inari Shrine (known as Ochobo-san) became a powerful driver of the local economy. A lively commercial district grew around the temple, attracting millions of pilgrims and tourists annually, turning the city into an important commercial and cultural center of Gifu Prefecture.
Establishment of Kiso Sansen National Government Park The opening of the country's largest state park in 1987 marked a shift in the territory's image: from a "dangerous flood zone" to a recreational gem. This event stimulated tourist flow and the development of the service sector.
Administrative Merger of 2005 The unification of the towns of Kaizu, Hirata, and Nanno allowed for the centralization of water resource management and municipal services. This gave an impetus to the comprehensive development of the urban environment and improved transport accessibility for residents of all three districts.
Architecture
Unique Hydraulic Urban Planning
The architectural character of Kaizu is inextricably linked to its geographic location in the lowlands between three rivers. The city's urban structure is unique in Japan, serving as a classic example of human adaptation to challenging natural conditions. Historically, the city did not develop around market squares or castles, but within waju — ring levees that protect settlements from flooding. This determined the dispersed nature of the buildings, where residential clusters resemble islands amidst rice fields.
Architectural Styles and Historical Eras
In Kaizu, it is difficult to find European styles like Gothic or Baroque. Instead, the landscape is dominated by the evolution of traditional Japanese architecture, transformed under the influence of the water and subsequent modernization.
Edo Period (1603–1868) — Folk Architecture and Mizuya: The main architectural feature of the region became mizuya — special protective structures. These are residential houses or warehouses built on high stone platforms (sometimes up to 3 meters high) to save property and lives during levee breaches. The style is characterized by utility, heavy wooden beams, and the presence of boats suspended under the eaves for evacuation purposes.
Meiji Period (1868–1912) — Engineering Modernism: During this period, the architectural focus shifted to civil engineering and hydraulic works. Under the influence of Western technology (particularly the Dutch school), large-scale sluice gates and reinforced embankments were built, changing the landscape and allowing for the expansion of safe building zones.
Modern Era (Since the 1980s) — Landscape Urbanism: The city's modern architecture is represented by functional public buildings and recreational facilities. The emphasis is on integrating buildings into park areas and creating observation decks.
Iconic Structures and Districts
The city's appearance is shaped by several key landmarks reflecting different facets of its history:
Chiyaho Inari Shrine (Ochobo-san): An example of traditional temple architecture with its characteristic torii gates and a complex system of wooden pavilions. The atmosphere of an old merchant town has been preserved around the temple, with dense low-rise buildings and narrow streets.
Kaizu City Historical Museum: The building is styled after an ancient castle, recalling the Takasu Domain that once existed here. It serves as a visual landmark and a repository of cultural memory.
Kiso Sansen Park Center Observation Tower: An example of a modern high-rise construction, allowing visitors to appreciate the scale of the hydraulic engineering works and the region's unique topography from a bird's-eye view.
Preserved Mizuya Houses: In old districts (such as the Hirata sector), one can still find private estates with historical mizuya elevations, which are protected as cultural heritage.
Notable People
Historical Figures and Rulers
Matsudaira Katamori (1836–1893) Role: Daimyo (feudal lord), military leader, ruler of the Aizu Domain.
Significance: One of the famous "Four Takasu Brothers" born in the local Takasu Domain (modern-day Kaizu). He played a key role in late Edo-period politics as the protector of Kyoto and patron of the Shinsengumi. His Kaizu origins are a source of pride for the townspeople.
Tokugawa Yoshikatsu (1824–1883) Role: Head of the influential Owari Tokugawa clan, politician.
Significance: The eldest of the Takasu brothers. A native of these lands, he reached the heights of power, becoming the ruler of Owari Province. During the Meiji Restoration, he was a supporter of modernization and the peaceful transfer of power to the Emperor.
Matsudaira Sadaaki (1847–1908) Role: Daimyo of the Kuwana Domain, Kyoto Shoshidai (the Shogun's representative in Kyoto).
Significance: The younger brother of Katamori and a native of Takasu. An active participant in the Boshin War on the side of the Shogunate. Along with his brothers, he symbolizes the influence of Kaizu natives on the fate of all Japan during a pivotal historical moment.
Matsudaira Yoshitatsu (1800–1862) Role: 10th Daimyo of the Takasu Domain.
Significance: Ruler of the local lands and father of the prominent "Four Takasu Brothers." His reign contributed to strengthening the status of the domain, which allowed his sons to occupy the highest state offices.
Heroes of the Struggle Against the Elements
Hirata Yukie (1704–1755) Role: Samurai, Karo (elder) of the Satsuma Domain.
Significance: Leader of the tragic and heroic project to protect the region from flooding (the Horeki Incident). Under his command, samurai built levees in extremely difficult conditions. He sacrificed his life, taking responsibility for the overexpenditure of funds and the deaths of his subordinates. He is revered as a guardian deity at the city's Chisui Shrine.
Johannis de Rijke (1842–1913) Role: Dutch civil engineer, foreign advisor to the Meiji government.
Significance: Developed a large-scale plan to separate the channels of the Kiso, Nagara, and Ibi rivers (the Kiso Sansen project). His engineering genius forever changed the geography of Kaizu, ridding the city of destructive floods and making the land suitable for safe living.