This city originally had two cores. One was a riverside post town along a highway linking Shinshu and Mikawa. The other was the castle town of a small 33,000-koku domain in the mountains to its east. A plains post and a mountain castle town. Two old towns of differing character were bound into one city in the Heisei mergers, and its municipal area became the third-largest in the prefecture. This city in the north of the Ina valley has kept its population around sixty thousand while carrying the two histories of plains and mountains. Ina’s numbers are the record of a city marked by a history that bound two cores — a highway post and a mountain-castle town — together.
A city opening onto the north of the Ina valley carved by the Tenryu River, in southern Nagano Prefecture. This city walked its history with two old towns of differing character as cores — a post town of the Sanshu Kaido passing along the riverside, and a domain’s castle town in the mountains to its east. The population held around sixty thousand: from 62,284 in 2000 and 62,869 in 2005, across the 2006 merger to 71,093 in 2010, then 68,271 in 2015 and 66,125 in 2020. What I (Atlas) want to read here is not the sign “Ina-valley city,” but the causal thread — how a history that bound two cores, a highway post and a mountain-castle town, is translated into the present population and finances.
01 · Pinning down the present Ina by its indicators
In the most recent Population Census the population is about 66,000 (66,125 in 2020). From 62,284 in 2000 and 62,869 in 2005, across the 2006 merger it jumped once to 71,093 in 2010, and then eased gently to 68,271 in 2015 and 66,125 in 2020. The step in the 2010 figure is not a sudden rise in population, but the result of adding mountain towns and villages to the municipal area through merger.
Look into the makeup and the figure of an Ina-valley city that bound a plains post and a mountain castle town appears. The share aged 65 and over rose from 20.8% in 2000 to 31.2% in 2020 — up about ten points over twenty years, past three in ten. Households with children were 22.1% in 2020. The childcare waitlist was zero in both 2024 and 2025. The Fiscal Capacity Index was 0.47 in FY2023 — its own tax revenue does not reach half of expenditure, a level with a large degree of reliance on the local allocation tax. The numbers show a city holding both plains and mountains within a broad area keeping its population around sixty thousand while raising the town’s age. Why it takes this shape cannot be read without going back to the history of the post and the castle town.
Source: Population Census (Statistics Bureau, MIC) / Local Government Finance Survey (MIC, Fiscal Capacity Index) / Status Report on Childcare Facilities (Children and Families Agency) / Real Estate Information Library (MLIT)
02 · The Sanshu Kaido post, the Takato mountain-castle town, and the Heisei merger — the history behind the numbers
This city’s skeleton is set by one core of a riverside highway post, another core of a mountain castle town, and the Heisei merger that bound the two. The first core is the highway post. The central urban area along the Tenryu River developed as post towns of the Sanshu Kaido, the artery of distribution linking Shinshu and Mikawa. The highway post passing through the plains was one of this city’s foundations.
The other core lies in the mountains to the east. There stood a mountain castle greatly rebuilt by a warlord of Kai in the Sengoku era, and in the Edo period it flourished as the castle town of a 33,000-koku domain. A plains post, and a mountain castle town. Two old towns of differing character and differing origins each layered their own history. In 2006, a new merger that added a mountain village to these two cores took effect, and the new city’s area, at about 667 square kilometers, became the third-largest in the prefecture. The Sanshu Kaido post, the Takato mountain-castle town, and the Heisei merger — this city’s shape stands on a history in which two cores, a plains post and a mountain castle town, were bound into one broad municipal area.
Source: Ina City / the Sanshu Kaido and the Takato castle town · 2006 merger (the central urban area along the Tenryu River developed as post towns of the Sanshu Kaido (Inabe-juku and others) linking Shinshu and Mikawa, while Takato to the east flourished as the 33,000-koku castle town of the Naito family (Takato Castle); the 2006-3-31 new merger of the former Ina City, Takato Town and Hase Village produced an area of about 667 km², the third-largest municipal area in the prefecture after Matsumoto and Nagano) / Ina City / Takato Castle (originally a castle of the Takato clan, greatly rebuilt by the Takeda of Kai in the Sengoku era; in the Edo period it flourished as the castle town of the Naito family)
03 · In a broad area binding plains and mountains, keeping the population around sixty thousand
What characterizes Ina is that, while carrying the two cores of a highway post and a mountain castle town, it keeps its population around sixty thousand. After jumping to 71,093 in 2010 through the 2006 merger, it eased to 66,125 in 2020, but that slope is gentle. It can be read that holding two cores of living within the area — a central plains urban area and a mountain castle town — has worked, in place of concentrating the population at one point, toward preventing a steep outflow. But some of the younger generation moved toward larger cities, and the town’s age has risen overall. That the share aged 65 and over reached 31.2% in 2020, past three in ten, is one sign of this.
On the other hand, the childcare waitlist was zero in both 2024 and 2025, and households with children were 22.1% in 2020. A Fiscal Capacity Index of 0.47 is a level where its own tax revenue does not reach half of expenditure, which can be read as a sign that, holding many mountain settlements within a broad area, administrative costs tend to mount. The city that bound plains and mountains in a broad area now keeps its population around sixty thousand, easing it down gently while raising the town’s age. The decline is gentle, aging is past three in ten, and fiscal stamina does not reach half. A riverside post, a mountain castle town, and the prefecture’s third-largest municipal area binding them — holding several places of living of differing character has written into Ina’s numbers both the stability of preventing a steep outflow and the mounting administrative costs.
Source: Population Census (Statistics Bureau, MIC) / Local Government Finance Survey (MIC, Fiscal Capacity Index) / Status Report on Childcare Facilities (Children and Families Agency)
04 · How a plains post and a mountain castle town were bound into one broad municipal area
Ina’s history is not one thing. It has a plains core: a post town of the Sanshu Kaido passing through the plains along the Tenryu River. It has a mountain core: the castle town of a 33,000-koku domain originating in a Sengoku mountain castle, in the mountains to the east. And those two cores of differing character were bound into one city in the Heisei merger, becoming the third-largest municipal area in the prefecture. The Ina valley carved by the Tenryu River raised the plains post and the mountain castle town separately, though near one another.
Ina is a city where a plains post and a mountain castle town were bound into one broad municipal area. From the Sanshu Kaido post and the Takato mountain-castle town, to the Heisei merger, to a population held around sixty thousand — the geography of the north of the Ina valley carved by the Tenryu River set two places of living, plains and mountains, near each other. A post that welcomed travelers by the river. A castle greatly rebuilt by a warlord of Kai in the mountains. That the two cores did not concentrate into one writes into the same municipal area, at once, both the stability of preventing a steep outflow of people and the mounting administrative costs.
Source: Ina City / the Sanshu Kaido and the Takato castle town · 2006 merger (the central urban area along the Tenryu River developed as post towns of the Sanshu Kaido (Inabe-juku and others) linking Shinshu and Mikawa, while Takato to the east flourished as the 33,000-koku castle town of the Naito family (Takato Castle); the 2006-3-31 new merger of the former Ina City, Takato Town and Hase Village produced an area of about 667 km², the third-largest municipal area in the prefecture after Matsumoto and Nagano) / Ina City / Takato Castle (originally a castle of the Takato clan, greatly rebuilt by the Takeda of Kai in the Sengoku era; in the Edo period it flourished as the castle town of the Naito family) / Population Census (Statistics Bureau, MIC)
05 · Atlas note — stability and cost are the front and back of a municipal area broadened by merger
Lay out Ina’s numbers and the indicators of an Ina-valley city that bound plains and mountains line up: a population held around sixty thousand, an aging rate of 31.2%, a 22.1% share of households with children, and fiscal capacity 0.47. But what I (Atlas) want to read as a certified public accountant is the point that the step in the 2010 figure of 71,093 is “not an increase in population, but the result of broadening the area through merger.” Even for figures that look the same as “the population rose,” a rise from young households flowing in and a rise from adding neighboring towns and villages to the area lead down entirely different paths thereafter. Ina’s step is the latter, and its population afterward turned to a gentle decline. It is a textbook case that a step in the figures must first be read by suspecting whether a merger took place.
Another point to consider is that this city “holds two cores of differing character — a plains post and a mountain castle town — within one municipal area.” The central plains urban area as a place of commuting and commerce, and the mountain castle town as a place of a different history and living, each hold people. To the extent that it is not single-point concentration, a steep outflow of people is held back more easily. But holding many mountain settlements within a broad area mounts administrative costs and lies behind the figure of fiscal capacity 0.47, which does not reach half. One city holds both the stability and the cost that breadth brings. The plains post holds people, the mountain castle town broadened the area, and that breadth produces the cost of fiscal capacity 0.47. Stability and cost are the front and back of the same breadth. The contour of the Ina-valley city was made of both.
Source: Population Census (Statistics Bureau, MIC) / Ina City / the Sanshu Kaido and the Takato castle town · 2006 merger (the central urban area along the Tenryu River developed as post towns of the Sanshu Kaido (Inabe-juku and others) linking Shinshu and Mikawa, while Takato to the east flourished as the 33,000-koku castle town of the Naito family (Takato Castle); the 2006-3-31 new merger of the former Ina City, Takato Town and Hase Village produced an area of about 667 km², the third-largest municipal area in the prefecture after Matsumoto and Nagano) / Ina City / Takato Castle (originally a castle of the Takato clan, greatly rebuilt by the Takeda of Kai in the Sengoku era; in the Edo period it flourished as the castle town of the Naito family)
Editor’s note: all figures and sources are drawn from official statistics. The prose follows Atlas’s voice, and AI (atlas-handcrafted-reverse-v1 (Daiki 2026-06-02)) handled the shaping of the text. Evaluative or predictive language (such as “a good buy” or “attractive”) is intentionally left out. Revision id: wave26w_