On this island there is almost no river that flows over the surface. The ground of the island, made of the remains of coral, drinks in the rain that falls and lets it seep into the depths of the earth. On this island poor in water, the people built a watertight wall in the depths of the ground, held back the water flowing underground, and made the world’s first large-scale underground dam. This coral island, which holds water in the depths of the ground to water its fields, and the islands around it, were bound into one by bridges and by merger. This land, a coral island without rivers, was established as a city when five municipalities were bound into one, and has still kept its population. Miyakojima City’s numbers are the record of a city inscribed with the past of a dam that holds water in the depths of the ground and its five islands.
A city of the islands that run roughly in the middle of the Ryukyu Islands, in Okinawa Prefecture. Because this city was newly established in 2005 when one city, one village and three towns of the islands were bound into one, the statistics cover the period from 2005 onward after the city’s establishment. The population has been kept almost level, from 53,493 in 2005 to 52,931 in 2020. What I (Atlas) want to read here is not the sign "a city of the southern islands," but the causal thread: how the past of a dam that holds water in the depths of the ground and its five islands is translated into today’s population and finances.
01 · Seeing the present Miyakojima in its numbers
In the latest Population Census the population is about 53,000 (52,931 in 2020). Because this city was newly established in 2005 when one city, one village and three towns of the islands were bound into one, the statistics cover the period from 2005 onward after the city’s establishment. From the 53,493 of that 2005, through 52,039 in 2010 and 51,186 in 2015, to 52,931 in 2020, it has been kept almost level, and in recent years has slightly increased.
Looking inside, the figure of a city of a coral island without rivers appears. The share aged 65 and over has risen from 24.7% in 2015 to 26.6% in 2020, yet still does not reach three in ten, and as an island city its age is young. The household-with-children share is 20.7% in 2020, and the crude birth rate is 9.9 per thousand in 2020 — high for a regional city. The Childcare Waitlist was zero in both 2024 and 2025. The Fiscal Capacity Index was 0.38 in fiscal 2023 — a level whose own tax revenue can cover only a little under four-tenths of expenditure, with a large degree of reliance on the local allocation tax. The figure shows in the numbers: the coral island without rivers keeps its population after the merger and leaves a comparatively young age. Why it takes this form cannot be read without going back to the past of an island without rivers, an underground dam, and the merger of five islands.
Source: Population Census (Statistics Bureau, MIC) / Local Government Finance Survey, Fiscal Capacity Index (MIC) / Childcare Facility Status Report (Children and Families Agency) / Real Estate Information Library (MLIT)
02 · A coral island without rivers, a dam that holds water in the depths of the ground, islands tied by bridges, the merger of five municipalities — the history behind the numbers
This city’s frame is set by the landform of a coral island without rivers, a dam that holds water in the depths of the ground, islands tied by bridges, and the merger of five municipalities. The starting layer is the coral island without rivers. The ground of this island is made of the remains of coral, and drinks in the rain that falls, letting it seep into the depths of the earth. That there is almost no river that flows over the surface, and that it is poor in water, was this island’s long challenge. The landform of a coral island without rivers was the foundation of this city.
On this island poor in water, the people held the water in the depths of the ground. They built a watertight wall in the depths of the ground, held back the water flowing underground, and made the world’s first large-scale underground dam. By this, it became possible to water the fields with the water held in the depths of the ground, and the island became an island of fields raising the sweet stalk. The path to becoming a city, too, mirrors this city. The largest island occupies the bulk of the islands, and some islands are tied by bridges. In 2005, one city, one village and three towns of the islands were newly bound into one, and the present city was established. A coral island without rivers, a dam that holds water in the depths of the ground, islands tied by bridges, and the merger of five municipalities — this city’s form stands upon the past of an underground dam and a merger inscribed by a coral island without rivers.
Source: Miyakojima City / underground dam (on an island of coral-reef origin with no rivers, the world’s first large-scale underground dam, which builds a watertight wall in the depths of the ground to hold back the groundwater, was constructed; sugarcane — overview) / Miyakojima City / islands and bridges (made up of the six islands of Miyako, Irabu, Shimoji, Ikema, Ogami and Kurima, with Miyako accounting for about 78% of the total area; Miyako and Irabu are tied by the Irabu Bridge — overview) / Miyakojima City (on 2005-10-1 Hirara City + Irabu Town + Ueno Village + Gusukube Town + Shimoji Town were newly established by merger; the Miyako Islands roughly in the middle of the Ryukyu Islands — overview)
03 · In a coral island without rivers, keeping the population after the merger
What characterizes Miyakojima is that, while it holds the past of a coral island without rivers, it keeps its population almost level after the merger. From the 53,493 of 2005, when the city was established, to the 52,931 of 2020, it has kept almost level over fifteen years, and in recent years has slightly increased. Though it is an island far across the sea from the mainland, behind this city keeping its population one can read that it has walked as an island of fields, watering its fields with the dam that holds water in the depths of the ground and raising the sweet stalk, and that in recent years bridges tying island to island were built. That the share aged 65 and over still does not reach three in ten at 26.6% in 2020, and that the crude birth rate is high for a regional city at 9.9 per thousand, show that the island leaves a comparatively young age.
On the other hand, the Childcare Waitlist was zero in both 2024 and 2025, and the household-with-children share is 20.7% in 2020. The Fiscal Capacity Index of 0.38 is a level whose own tax revenue can cover only a little under four-tenths of expenditure, showing the large degree of reliance on the local allocation tax seen in common across the lands of islands set off by the sea from the mainland. The coral island without rivers now walks on, keeping its population after the merger and leaving a comparatively young age. The population is kept almost level, the age is young for an island city, and the fiscal stamina is not thick on tax revenue alone — while many island cities greatly lose population, the device of holding water in the depths of the ground and the bridges tying the islands support the living of this coral island.
Source: Population Census (Statistics Bureau, MIC) / Local Government Finance Survey, Fiscal Capacity Index (MIC) / Childcare Facility Status Report (Children and Families Agency)
04 · An island without rivers that held water in the depths of the ground and became an island of fields
In Miyakojima, the weakness of a landform with almost no river flowing over the surface is inscribed first. The ground made of the remains of coral drinks in the rain that falls and lets it seep into the depths of the earth. Against that poverty of water, the people built a watertight wall in the depths of the ground and made the world’s first large-scale underground dam, holding back the water flowing underground. The largest island occupies the bulk of the islands, and some islands are tied by bridges.
From a coral island without rivers, to a dam that holds water in the depths of the ground, to islands tied by bridges, to the merger of five municipalities. The landform of an island without rivers made of the remains of coral bred the device of holding water in the depths of the ground, and made it hold an island of fields raising the sweet stalk. In this position of the Miyako Islands, a land without rivers and an underground dam overlap, and the present figure of Miyakojima City is there.
Source: Miyakojima City / underground dam (on an island of coral-reef origin with no rivers, the world’s first large-scale underground dam, which builds a watertight wall in the depths of the ground to hold back the groundwater, was constructed; sugarcane — overview) / Miyakojima City / islands and bridges (made up of the six islands of Miyako, Irabu, Shimoji, Ikema, Ogami and Kurima, with Miyako accounting for about 78% of the total area; Miyako and Irabu are tied by the Irabu Bridge — overview) / Miyakojima City (on 2005-10-1 Hirara City + Irabu Town + Ueno Village + Gusukube Town + Shimoji Town were newly established by merger; the Miyako Islands roughly in the middle of the Ryukyu Islands — overview)
05 · Atlas’s note — in a coral island without rivers, reading the paradox of the device that the lack of water bred
Lay out Miyakojima’s numbers and the indicators of a city of a coral island that leaves a comparatively young age line up: a population almost level after the merger, an aging rate of 26.6%, a household-with-children share of 20.7%, a crude birth rate of 9.9, and a fiscal capacity of 0.38. Reading as one who, by profession, cannot help chasing the habits of numbers, what I want to read here is the overlap of landform and device by which this island overcame the poverty of water — "the ground made of the remains of coral drinks in the rain, and there is almost no river flowing over the surface" — with the device of "a watertight wall built in the depths of the ground, holding back the groundwater: the world’s first large-scale underground dam." The island’s weakness of having no river bred the device, found nowhere else, of holding water in the depths of the ground. The constraint of the landform, on the contrary, bred a solution found nowhere else — this chain explains the island of Miyakojima well.
Another thing I want to consider is that this island, far across the sea from the mainland, keeps its population almost level and keeps its crude birth rate high for a regional city at 9.9 per thousand. While many island cities greatly lose population, this island keeps its population. That it waters its fields with the water held in the depths of the ground, and that in recent years bridges tying island to island were built, support the living of the island, one can read.
Because it was an island without water, the world’s first device for holding water in the depths of the ground was born — how to hold that paradox is for each person who lives on the island to decide.
Source: Population Census (Statistics Bureau, MIC) / Miyakojima City / underground dam (on an island of coral-reef origin with no rivers, the world’s first large-scale underground dam, which builds a watertight wall in the depths of the ground to hold back the groundwater, was constructed; sugarcane — overview) / Miyakojima City / islands and bridges (made up of the six islands of Miyako, Irabu, Shimoji, Ikema, Ogami and Kurima, with Miyako accounting for about 78% of the total area; Miyako and Irabu are tied by the Irabu Bridge — overview) / Miyakojima City (on 2005-10-1 Hirara City + Irabu Town + Ueno Village + Gusukube Town + Shimoji Town were newly established by merger; the Miyako Islands roughly in the middle of the Ryukyu Islands — overview)
Editor’s note: all figures and sources are drawn from official statistics. The prose follows Atlas’s voice, and AI (atlas-handcrafted-reverse-v1 (wave33-west 2026-06-04)) handled the shaping of the text. Evaluative or predictive language (such as “a good buy” or “attractive”) is intentionally left out. Revision id: wave33w_