On this island remain the traces of a royal capital of some two thousand years ago. A small state across the sea, which an old Chinese book recorded — the capital of that state’s king is held to have been on this island. In the Yayoi age, this was a trading place linking Kyushu and the peninsula across the sea, and the remains of a landing wharf and the goods that came over the sea came out from under the earth. This border island holding the remains of a royal capital of the sea was established as a city by binding four towns into one, and has now quietly lost population. Iki’s numbers are the record of a town in which a border island and Yayoi trade are inscribed.
A city of an island of Nagasaki Prefecture, floating between mainland Kyushu and Tsushima. Because this city was established in 2004 by binding four towns on the island anew into one, the statistics cover the period from 2005, after the city’s establishment, on. The population has fallen from the 31,414 of 2005 to the 24,948 of 2020. What I (Atlas) want to read here is not the sign "an island city of the prefecture’s north," but the causal thread: how the past of a border island and Yayoi trade is translated into today’s population and finances.
01 · Seeing the present Iki in its numbers
In the latest Population Census the population is about 25,000 (24,948 in 2020). Because this city was established in 2004 by binding four towns on the island anew into one, its population statistics as a city cover the period from 2005, after the establishment, on. From the 31,414 of 2005, through the 29,377 of 2010, the 27,103 of 2015, to the 24,948 of 2020, it has fallen.
Looking inside, the figure of a city of an island floating between mainland Kyushu and Tsushima appears. The share aged 65 and over rose from 35.5% in 2015 to 38.6% in 2020, nearing four in ten. The household-with-children share is 20.7% in 2020, and the Childcare Waitlist was zero in both 2024 and 2025. The Fiscal Capacity Index was 0.22 in fiscal 2023 — a level able to cover only a little over two-tenths of expenditure with its own tax revenue, with a large degree of reliance on the local allocation tax. The island where a royal capital was placed two thousand years ago now loses population and advances its aging after the merger. Why it takes this form cannot be read without going back to the past of the border, the trade and the merger.
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 · The island between Kyushu and the peninsula, the Yayoi royal capital of the sea, the border island, a merger of four towns — the history behind the numbers
What supports Iki’s past is the island’s position floating between Kyushu and the peninsula across the sea, the Yayoi royal capital of the sea, the character of a border island, and the merger of four towns. The oldest layer is the island’s position and the royal capital. This island floats between mainland Kyushu and Tsushima, and beyond lies the peninsula across the sea. In the Yayoi age, this was a trading place linking Kyushu and the peninsula, and the capital of the king of a small state, which an old Chinese book recorded, is held to have been on this island. From the traces of that royal capital came the remains of a landing wharf, old even within the country, and the goods that came over the sea, designated a National Special Historic Site. That it was a trading place crossing the sea is this island’s oldest foundation.
This island has continued to lie on the way of the road crossing the sea. Lying on the route linking Kyushu and the peninsula, this island, together with Tsushima, has continued to mark the border between states, and is still counted, together with Tsushima and Goto, as a border island in the Japan Heritage. The newest layer is the path to becoming a city. In 2004 the four towns on the island were bound anew into one, and the present city was established. The island between Kyushu and the peninsula, the Yayoi royal capital of the sea, the border island, the merger of four towns — the land that piled these four layers in order of age is the present Iki.
Source: Iki City / the Harunotsuji Site (a National Special Historic Site held to be the royal capital of the state of Iki recorded in the "Account of the Wa" in the Wei Chronicle; in the Yayoi period a trading place linking Kyushu and the Korean peninsula, where one of Japan’s oldest landing-wharf remains was excavated — overview) / Iki City / the border islands (an island lying between mainland Kyushu and Tsushima; the Harunotsuji Site is a constituent of the Japan Heritage "Border Islands — Iki, Tsushima and Goto" — overview) / Iki City (established on 2004-3-1 by the new merger of Gonoura, Katsumoto, Ashibe and Ishida Towns on the island — overview)
03 · On an island holding the remains of a royal capital of the sea, losing population after the merger
What characterizes Iki is that, while it holds the past of a Yayoi royal capital of the sea, it is losing population after the merger. From the 31,414 of 2005, when the city was established, to the 24,948 of 2020, over six thousand were lost over fifteen years. Even on this island that was once a trading place linking Kyushu and the peninsula, from modern times on it became an island land centered on fishery and agriculture, and one can read that some of the younger generation moved toward the larger cities and the Kyushu mainland and the town’s age as a whole rose. That the share aged 65 and over neared four in ten at 38.6% in 2020 is an expression of that.
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 0.22 is a level able to cover only a little over two-tenths of expenditure with its own tax revenue, showing the large degree of reliance on the local allocation tax seen in common across island lands cut off from the mainland by sea. The population fell after the merger, the aging neared four in ten, and the body of the finances is not thick on tax revenue alone. What combination of numbers the island that held an ancient royal capital has now settled into — that forms its image only when population, age and finances are layered on a single sheet.
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 on the way of the road crossing the sea held a Yayoi royal capital
The functions Iki holds are not one. It has the face of an island on the way of the road crossing the sea, floating between mainland Kyushu and Tsushima, with the peninsula across the sea beyond. It also has the face of a Yayoi royal capital of the sea, a trading place linking Kyushu and the peninsula in the Yayoi age, keeping the traces of the capital of the king of a small state, which an old Chinese book recorded, as a National Special Historic Site. The landform and position of floating between Kyushu and the peninsula brought to this island both the role of a trading place and the royal capital.
An island on the way of the road crossing the sea held a Yayoi royal capital — that is the town Iki is. From the island between Kyushu and the peninsula, to the Yayoi royal capital of the sea, the border island, and the merger of four towns, what set the skeleton was the geography of "an island floating between mainland Kyushu and Tsushima." Precisely because it lay on the way of the road crossing the sea, some two thousand years ago this became a key place enough for the royal capital of a small state to be placed here. At the foot of the now-quiet island, the remains of a landing wharf of that age sleep.
Source: Iki City / the Harunotsuji Site (a National Special Historic Site held to be the royal capital of the state of Iki recorded in the "Account of the Wa" in the Wei Chronicle; in the Yayoi period a trading place linking Kyushu and the Korean peninsula, where one of Japan’s oldest landing-wharf remains was excavated — overview) / Iki City / the border islands (an island lying between mainland Kyushu and Tsushima; the Harunotsuji Site is a constituent of the Japan Heritage "Border Islands — Iki, Tsushima and Goto" — overview) / Iki City (established on 2004-3-1 by the new merger of Gonoura, Katsumoto, Ashibe and Ishida Towns on the island — overview)
05 · Atlas’s note — on an island holding the remains of a royal capital of the sea, an ancient key place and the numbers of an island land overlap
Lay out Iki’s numbers and the indicators of a city of an island floating between mainland Kyushu and Tsushima line up: a population falling after the merger, an aging rate of 38.6%, a household-with-children share of 20.7%, and a fiscal capacity of 0.22. But when I (Atlas), as a certified public accountant, read these, what I want to read here is the singularity of this island’s past — that "in the Yayoi age it was a trading place linking Kyushu and the peninsula across the sea, and it still holds the traces of that royal capital under the earth." Because of the position of lying on the way of the road crossing the sea, some two thousand years ago this was a trading place enough for the royal capital of a small state to be placed here. The chain by which the position of crossing the sea gave this island its role in antiquity set this island’s history.
Another thing I want to consider is the thinness of the tax revenue and the height of the age — a Fiscal Capacity Index of 0.22 and an aging rate of 38.6%. Because it is an island cut off from the mainland by sea, industry is hard to draw in and the tax source is not thick. Even the island that was once the royal capital of trade crossing the sea has, from modern times on, lost that role and, as an island land centered on fishery and agriculture, lost population and advanced its aging to near four in ten.
The key place where the royal capital of a small state was placed two thousand years ago now holds the thin tax source and the high age of an island land cut off by sea. The same position of "on the way of the road crossing the sea" called in a royal capital in antiquity, and now works as the distance that makes industry hard to draw in. Whether to walk this island as the traces of a Yayoi royal capital of the sea, or to view it as an island land where fishery and agriculture continue, changes with what one wishes to visit. The key place where the royal capital of a small state was placed two thousand years ago now holds the thin tax source and the high age of an island land cut off by sea.
Source: Population Census (Statistics Bureau, MIC) / Iki City / the Harunotsuji Site (a National Special Historic Site held to be the royal capital of the state of Iki recorded in the "Account of the Wa" in the Wei Chronicle; in the Yayoi period a trading place linking Kyushu and the Korean peninsula, where one of Japan’s oldest landing-wharf remains was excavated — overview) / Iki City / the border islands (an island lying between mainland Kyushu and Tsushima; the Harunotsuji Site is a constituent of the Japan Heritage "Border Islands — Iki, Tsushima and Goto" — overview) / Iki City (established on 2004-3-1 by the new merger of Gonoura, Katsumoto, Ashibe and Ishida Towns on the island — 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 (wave31-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: wave31w_