Tsuyama-shi

In the 2020 Population Census the population of Tsuyama-shi is 99,937 — about 100,000. The first thing I want to set down here is that the sharp rise of more than twenty thousand, from 90,156 in 2000 to 110,569 in 2005, is not the result of people naturally increasing. It owes to the 2005 annexation of three neighboring towns and one village, and the step in the figures mirrors that merger.

With that set down, looking inside the post-merger figures, the population fell by more than ten thousand over fifteen years, from 110,569 in 2005 to 99,937 in 2020. Those under 15 thinned by more than four thousand, from 16,618 in 2005 to 12,449 in 2020. The share aged 65 and over rose from 19.4% in 2000 to 30.6% in 2020, passing three in ten. Households with children make up 20.9% (2020), the Childcare Waitlist has been zero in recent years, and the Fiscal Capacity Index was 0.51 in fiscal 2023. The numbers show a castle town widened by merger quietly growing older. Why it takes this shape cannot be read without tracing the history of the highway and the castle town.

Tsuyama’s skeleton is set by a castle town that a single daimyo laid out along the highway. Its builder was Mori Tadamasa, the youngest brother of Mori Ranmaru, known as a page who served Oda Nobunaga. Made lord of the whole province of Mimasaka for his service at the Battle of Sekigahara, Tadamasa began, from 1604, to build Tsuyama Castle at the confluence of the Yoshii and Miya rivers. It was a sturdy, massive hilltop castle set at the strategic point holding the Izumo Highway, which breaks through from Izumo Province toward Harima Province. A castle that held the highway was this town’s starting point.

The castle town that opened at the foot of that castle took shape stretching long east-to-west along the Izumo Highway, on the left bank of the Yoshii River. What is distinctive is that along the highway, within a stretch of about three kilometers, as many as eighteen key-shaped bends — kagi-magari — were set. These were devised to break the line of sight of an attacking enemy and hinder its advance; the castle town itself carried a military preparedness. A castle that held the highway, and a castle town with a strong military cast, were set at the center of the basin.

The Joto on the east side of this castle town and the Josai on the west were later each selected as Important Preservation Districts for Groups of Traditional Buildings, as districts where the old townscape remains. What decided the shape of the present municipal area was the Heisei-era merger. In 2005 Tsuyama-shi annexed Kamo Town, Awa Village, Shobaku Town, and Kume Town, widening into a broad municipal area embracing the towns and villages around the basin. Beginning with Mori Tadamasa’s highway castle, flourishing as a castle town with a strong military cast, and widened by merger — this town’s form stands on the history of the highway and the castle town.

What characterizes Tsuyama-shi is that, after the municipal area widened by merger, the population fell steadily and aging passed three in ten. Over the fifteen years after the merger the total population fell by more than ten thousand, and those under 15 thinned by more than four thousand. Without large inflow, the generations already living there simply grow older in place — a form common to the central cities of Mimasaka. A thinning of births and an outflow of the younger generation both bear on it.

The figures for living infrastructure mirror both the merger and the maturity. Elementary schools rose from 19 to 28 in the 2005 merger, as the school networks of the annexed towns and villages were bound in as they were. Since then they have held around 27, and even as children fall, the school network dispersed across the wide municipal area is broadly kept. The Childcare Waitlist has held at zero in recent years, but this owes strongly to a side where supply and demand balance as the number of children thins. Flourishing as Mori Tadamasa’s highway castle town and embracing the basin’s surroundings through merger, the center of Mimasaka has now entered a mature phase poor in inflow. The total population falls, children thin, aging passes three in ten. The loss of more than ten thousand and the school network held around 27 look like separate figures, but they are the front and back of the same phase — a maturity poor in inflow.

In Tsuyama, several faces as a castle town are inscribed. One is its character as a castle town centered on Tsuyama Castle, set at the strategic point holding the Izumo Highway; the castle town stretched long east-to-west along the highway, and the key-shaped bends that confuse the enemy still convey this town’s making. Another is the Joto and Josai districts, which keep the old townscape and were each selected as Important Preservation Districts for Groups of Traditional Buildings. And the municipal area bound by the 2005 merger holds, within one city, the castle town and the former towns and villages around the basin.

That Mori Tadamasa built a castle at the strategic point holding the highway that breaks through toward Izumo set down a castle town stretched long east-to-west, holding the key-shaped bends that confuse the enemy. Both the old townscape of Joto and Josai and the former towns and villages around the basin, taken in by the 2005 merger, begin from that castle town. On the basin through which the Yoshii River flows, the Izumo Highway and the castle town folded over one another — the military logic of holding the highway still governs the skeleton of the town of Tsuyama.