This city holds a living volcano. A little over thirty years ago, a volcano that had slept for nearly two hundred years woke, and the mass of hot eruptive cloud that flowed down took human lives. But the same volcano has welled up hot water from more than 1,300 years ago, and has raised a hot-spring resort chosen as Japan’s first national park. The fire that takes life and the fire that gives hot water dwell in the same single mountain. This peninsula of volcanic geology and hot springs, having bound seven towns into one to become a city, has quietly lost population after the merger. Unzen’s numbers are the record of a town in which the memory of eruption and recovery is inscribed.
A city that opens in the west of the Shimabara Peninsula of Nagasaki Prefecture. Because this city was established in 2005 by binding seven towns anew into one, its population statistics as a city cover the period from 2010, after the merger, on — the period that the Census reflects. From the 47,245 of 2010 to the 41,096 of 2020, it has decreased. What I (Atlas) want to read here is not the sign "a city of the Shimabara Peninsula," but the causal thread: how the memory of eruption and recovery is translated into today’s population and finances.
01 · Seeing the present Unzen in its numbers
In the latest Population Census the population is about 41,000 (41,096 in 2020). Because this city was established in 2005 by binding seven towns anew into one, its population statistics as a city cover the period from 2010, after the merger, on — the period the Census reflects. From the 47,245 of 2010, to the 44,115 of 2015, to the 41,096 of 2020, it has decreased.
Looking inside, the figure of a city of the peninsula holding the volcano and the hot springs appears. The share aged 65 and over rose from 31.7% in 2015 to 35.7% in 2020, passing three in ten by a wide margin. The household-with-children share is 20.5% (2020), and the crude birth rate is 5.9 per thousand in 2020. The Childcare Waitlist was zero in both 2024 and 2025. The Fiscal Capacity Index was 0.28 in fiscal 2023 — a level able to cover only a little under three-tenths of expenditure with its own tax revenue, with a large degree of reliance on the local allocation tax. At the foot of the volcano that erupted a little over thirty years ago, the population has fallen after the merger and the aging has passed three in ten by a wide margin. Why it takes this form cannot be read without going back to the past of the volcano, the hot springs and the eruption.
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 living volcano, hot springs of more than 1,300 years, eruption and a global geopark, a merger of seven towns — the history behind the numbers
What supports Unzen’s past is the living volcano, the hot springs of more than 1,300 years, the eruption and the recovery from it, and the merger of seven towns. The oldest layer is the volcano and the hot springs. At the center of this peninsula rises a living volcano, and its heat, warming the water deep in the earth, has welled up hot water from more than 1,300 years ago. The hot-spring resort spreading in the high mountains was chosen as Japan’s first national park. A volcano that may take life brings, at the same time, the gift of hot water — this duality is the foundation of this land.
This volcano woke in recent years. A little over thirty years ago, a volcano that had slept for nearly two hundred years erupted, and the mass of hot eruptive cloud that flowed down took human lives. That disaster, and the recovery from it, and the relation of people to the landforms the volcano makes, were later recognized — the first in Japan — as a global geopark holding up "the coexistence of people and volcanoes." The newest layer is the path to becoming a city. In 2005 the seven towns in the west of the peninsula were bound anew into one, and the present city was established. The living volcano, the hot springs of 1,300 years, the eruption and the global geopark, and the merger of seven towns — the land that piled these four layers is the present Unzen.
Source: Unzen City / Unzen Hot Spring (a hot-spring resort at about 700 m elevation near the center of the Shimabara Peninsula, with a history of spring-water use of more than 1,300 years; designated in 1934 as Japan’s first national park — overview) / Unzen City / Mount Fugen and the Geopark (Mount Fugen erupted in 1990–1991 and its pyroclastic flows caused fatalities; the Shimabara Peninsula was certified in 2009 as Japan’s first UNESCO Global Geopark under the theme "the coexistence of people and volcanoes" — overview) / Unzen City (established on 2005-10-11 by the new merger of Kunimi, Mizuho, Azuma, Aino, Chijiwa, Obama and Minamikushiyama Towns; western Shimabara Peninsula; Obama Hot Spring — overview)
03 · In a peninsula of volcanic geology and hot springs, losing population after the merger
What characterizes Unzen is that, while it holds the past of a peninsula of volcanic geology and hot springs, it is losing population after the merger. From the 47,245 of 2010, seen in the city area after the merger, to the 41,096 of 2020, some six thousand were lost over ten years. Even in this land that holds hot springs of more than 1,300 years and is counted as a global geopark, because it is a peninsula far from the larger cities, one can read that some of the younger generation moved out of the town in search of work and study, and the town’s age as a whole rose. That the share aged 65 and over passed three in ten by a wide margin at 35.7% in 2020 is an expression of that.
On the other hand, the Childcare Waitlist was zero in both 2024 and 2025, the household-with-children share is 20.5% in 2020, and the crude birth rate is 5.9 per thousand in 2020. The Fiscal Capacity Index of 0.28 is a level able to cover only a little under three-tenths of expenditure with its own tax revenue, showing the large degree of reliance on the local allocation tax seen in common across peninsular lands. The population fell after the merger, the aging passed three in ten by a wide margin, and the body of the finances is not thick on tax revenue alone. What overlap of numbers the peninsula that came through eruption has now settled into — that comes into view only when population, age and finances are laid out 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 · A living volcano held both the fire that takes life and the fire that gives hot water
The functions Unzen holds are not one. At the center of the peninsula rises a living volcano, holding the face of a living volcano that, after sleeping for nearly two hundred years, woke and took human lives. It also holds the face of a hot-spring land, where the heat of that volcano, warming the water deep in the earth, welled up hot water from more than 1,300 years ago and was chosen as Japan’s first national park. And it holds the face of a peninsula of geology, leaving the disaster and recovery of the eruption, and the relation of people to the landforms the volcano makes, as a global geopark under "the coexistence of people and volcanoes." A living volcano held, in the same single mountain, the fire that takes life and the fire that gives hot water.
A living volcano held both the fire that takes life and the fire that gives hot water — that is the town Unzen is. From the living volcano, to the hot springs of 1,300 years, the eruption and the global geopark, and the merger of seven towns, what set the skeleton was the geography of "a peninsula holding a living volcano." The same mountain that took human lives a little over thirty years ago has welled up hot water from 1,300 years back. That a single mountain holds that breadth of time has become the weight of this town.
Source: Unzen City / Unzen Hot Spring (a hot-spring resort at about 700 m elevation near the center of the Shimabara Peninsula, with a history of spring-water use of more than 1,300 years; designated in 1934 as Japan’s first national park — overview) / Unzen City / Mount Fugen and the Geopark (Mount Fugen erupted in 1990–1991 and its pyroclastic flows caused fatalities; the Shimabara Peninsula was certified in 2009 as Japan’s first UNESCO Global Geopark under the theme "the coexistence of people and volcanoes" — overview) / Unzen City (established on 2005-10-11 by the new merger of Kunimi, Mizuho, Azuma, Aino, Chijiwa, Obama and Minamikushiyama Towns; western Shimabara Peninsula; Obama Hot Spring — overview)
05 · Atlas’s note — in a peninsula of volcanic geology and hot springs, taking on disaster and gift together
Lay out Unzen’s numbers and the indicators of a city of the peninsula holding the volcano and the hot springs line up: a population falling after the merger, an aging rate of 35.7%, a household-with-children share of 20.5%, and a fiscal capacity of 0.28. But when I (Atlas), as a certified public accountant, read these, what I want to read here is the duality of the volcano — that this town "holds, as the same single mountain, both a volcano that may take life and a volcano that gives hot water." The same volcano that woke after sleeping for nearly two hundred years and took human lives with a mass of hot eruptive cloud has welled up hot water from more than 1,300 years ago and raised Japan’s first national park. That the fire that brings disaster and the fire that brings gift dwell in the same single mountain is something peculiar to this town.
Another thing I want to consider is that this town took on that duality with the words "the coexistence of people and volcanoes," and was recognized — the first in Japan — as a global geopark. To take on the volcano not only as disaster but also as a place of gift and learning. That stance translates the memory of eruption into a resource of tourism and learning.
The same mountain that took lives a little over thirty years ago has welled up hot water from 1,300 years back; this peninsula took on that breadth of time not by erasing the disaster but as a way of living with the volcano. Whether to view this land as a peninsula of geology inscribing the memory of eruption, or to visit it as a hot-spring village of 1,300 years, changes with what one turns one’s heart toward. The same mountain that took lives a little over thirty years ago has welled up hot water from 1,300 years back — this peninsula took on that breadth of time as a way of living with the volcano.
Source: Population Census (Statistics Bureau, MIC) / Unzen City / Unzen Hot Spring (a hot-spring resort at about 700 m elevation near the center of the Shimabara Peninsula, with a history of spring-water use of more than 1,300 years; designated in 1934 as Japan’s first national park — overview) / Unzen City / Mount Fugen and the Geopark (Mount Fugen erupted in 1990–1991 and its pyroclastic flows caused fatalities; the Shimabara Peninsula was certified in 2009 as Japan’s first UNESCO Global Geopark under the theme "the coexistence of people and volcanoes" — overview) / Unzen City (established on 2005-10-11 by the new merger of Kunimi, Mizuho, Azuma, Aino, Chijiwa, Obama and Minamikushiyama Towns; western Shimabara Peninsula; Obama Hot Spring — 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_