Mihara-shi

In the 2020 Population Census it is 90,573, still above ninety thousand. To read this city’s population, one must account for a merger. In 2005 Mihara widened its city area by adding three neighboring towns. The population of the former Mihara City before the merger was 82,081 in 2000, and after the merger it was 104,196 in 2005. From there it has fallen gently — 100,509 in 2010, 96,194 in 2015, 90,573 in 2020. The step in population between 2000 and 2005 in this article mirrors the widening of the city area by this merger.

Looking inside, a figure befitting a Seto Inland Sea harbor town appears. The share aged 65 and over rose from 22.3% in 2000 to 35.5% in 2020, well above three in ten. The household-with-children share was 18.3% in 2020, somewhat low, and the Childcare Waitlist was zero in both 2024 and 2025. The Fiscal Capacity Index was 0.53 in fiscal 2023 — a middling level, able to cover a little over half of expenditure with its own tax revenue. The figure of the castle town of a castle that floats on the sea, losing population on the post-merger city area while advancing in aging, appears in the numbers. Why it takes this shape cannot be read without going back over the history of a naval-clan castle town and a Seto Inland Sea harbor.

What set this town is the castle built by joining seaside islands, and its position near the center of the Seto Inland Sea, the key point of both sea and land. The central layer is the castle. In the Warring States era, a wise general of a clan that commanded the Seto Inland Sea is said to have begun building a castle on reclaimed land that joined small seaside islands. Because at high tide the castle seemed to float on the sea, it was called the Floating Castle. That he chose this land looking out over both sea and land and built the castle is this town’s central history.

Upon this castle town, harbor and highway were layered. This town faces near the center of the Seto Inland Sea and held a fine harbor with calm waters. From of old it prospered as a key point of sea traffic linking the Kinki and Kyushu regions and connecting also to Shikoku, and on land it bore the role of a key point of an old highway. To be the key point of both sea and land at once is the meaning of this town’s position. The road by which it became a city mirrors this town, too. In the mid-1930s several towns and villages merged to become a city, and in 2005 it widened the city area by adding three neighboring towns. A castle that floats on the sea, a wise general of a clan that commanded the Seto Inland Sea, a fine Seto Inland Sea harbor, and a key point of the old San-yo Road. Upon this land that combined the key points of both sea and land, the history of the castle and the history of the harbor are folded together — and there is the present Mihara.

What characterizes Mihara is that, while bearing the history of being the castle town of a castle that floats on the sea, it loses population and advances in aging on the post-merger city area. About fourteen thousand fell over fifteen years, from 104,196 in the post-merger 2005 to 90,573 in 2020. Even in this town that prospered as a fine Seto Inland Sea harbor and as a key point of sea and land, one can read that a part of the young generation moved to large nearby cities and the age of the whole town rose. That the share aged 65 and over rose well above three in ten at 35.5% in 2020 is its expression. That the lands added by the merger were originally mountain and coastal areas of higher age can also be read as bearing upon the aging of the whole city.

Meanwhile the Childcare Waitlist was zero in both 2024 and 2025. That the household-with-children share was somewhat low at 18.3% in 2020 can also be read as the reverse side of the town’s age having risen. The Fiscal Capacity Index of 0.53 is a level able to cover a little over half of expenditure with its own tax revenue, in the middle range. One can read that the income of households living in the Seto Inland Sea harbor town supports the tax source at a middling level. The population rose after the merger and then fell, the aging passed well above three in ten, and the fiscal strength is middling — a harbor town that prospered as a key point of sea and land now slowly raises its age on a city area widened by merger. That figure cannot be grasped from the single line of population alone.

Mihara’s origin is gathered into the single move of building a castle on reclaimed land that joined small seaside islands. In the Warring States era, a wise general of a clan that commanded the Seto Inland Sea chose this land, where at high tide the castle seemed to float on the sea. Befitting a clan that made the sea its place of livelihood, it was a choice of site looking out over both sea and land.

Upon this castle town, harbor and highway are layered. Near the center of the Seto Inland Sea, as a fine harbor with calm waters, it became a key point of the sea linking Kinki and Kyushu and connecting also to Shikoku, and on land it doubled as a key point of an old highway. A castle upon the sea, and a harbor that is the key point of both sea and land. A single position — near the center of the Seto Inland Sea — drew the two together.