Remote Islands in NumbersJapan's islands and Karatsu's seven inhabited islands

Karatsu's islands, in numbers

All of Saga Prefecture's remote islands are the seven inhabited islands of Karatsu City: Takashima, Kashiwajima, Ogawa, Kakara, Matsushima, Madara and Mukushima. This page lists, from national, prefectural and city documents, the number of islands and island population in Japan, and the population, ferries, schools and public spending of Saga's seven islands. In the 2020 census the seven islands had 1,203 people in 577 households (Saga Prefecture).

This page is part of the Karatsu Data Bank by Karatsu Farm&Food, an NPO in Karatsu. Since FY2023 we have run environmental education with the school of one Karatsu island each year (Island ESD). The page gives no conclusions or evaluations, only the figures and statements found in the documents. Values we calculated are marked "our calculation". Values read from charts are not used. English renderings of Japanese documents are our translations; the original text takes precedence.

Category	Islands	Population (2020)	Law (year enacted)
All islands of Japan	14,125	-	-
Remote islands (excluding Honshu, Hokkaido, Shikoku, Kyushu and Okinawa Island)	14,120	-	-
Inhabited islands	417	-	-
Areas designated under the Remote Islands Development Act	255 (77 areas)	339,211	Remote Islands Development Act (1953)
Designated remote islands of Okinawa	38	126,103	Okinawa Promotion Special Measures Act (2002; earlier law 1971)
Amami Islands	8	104,281	Amami Islands Promotion and Development Special Measures Act (1954)
Ogasawara Islands	4	2,929	Ogasawara Islands Promotion and Development Special Measures Act (1969)
Not covered by the four laws above	112	-	-
Specified inhabited remote border islands (part of the 255)	71 (15 areas)	244,998	Inhabited Remote Border Islands Act (2016)

How many islands Japan has, and which law covers them

Japan consists of 14,125 islands, of which 14,120 are remote islands. Of these, 255 inhabited islands lie in areas designated under the Remote Islands Development Act (1953). They span 77 areas, 26 prefectures and 111 municipalities, cover 5,313 km² (1.41% of Japan) and have 340,000 residents (0.27% of Japan) (Ministry of Land, Infrastructure, Transport and Tourism (MLIT)).

Of the 417 inhabited islands, 255 are covered by the Remote Islands Development Act, 50 by separate laws for Okinawa (38), Amami (8) and Ogasawara (4), and the remaining 112 by none of these laws (MLIT). Under the 1953 act, the national government designates areas and prefectures draw up island development plans. In the 2020 census, the 38 designated islands of Okinawa had 126,103 people (Okinawa Prefecture), the eight Amami islands 104,281 and the four Ogasawara islands 2,929 (MLIT).

The Inhabited Remote Border Islands Act (2016) defines inhabited remote border island areas as inhabited islands in areas that include an island on the baseline of Japan's territorial sea, and lists in an annex the specified areas where keeping the community going is especially necessary (Cabinet Office). The specified areas are 15 areas with 71 islands (8 prefectures, 29 municipalities) and had 244,998 people in the 2020 census. Inhabited remote border island areas as a whole are 29 areas with 148 islands (Cabinet Office).

An amendment of 15 July 2026 (Act No. 54 of 2026) adds Teuri and Yagishiri (Hokkaido), Tobishima (Yamagata), Awashima (Niigata) and Niijima and Shikinejima (Tokyo) to the specified areas from 1 April 2027, and extends the act to 31 March 2037. The amended annex lists 19 areas with 77 islands (our count from the annex). Karatsu's seven islands are not in the annex before or after the amendment (Cabinet Office).

Island population	Islands	Total population	Share of islands	Share of population	Karatsu's islands
Under 10	33	170	12.9%	0.1%	-
10–99	90	3,777	35.3%	1.1%	Matsushima, Mukushima
100–299	63	11,583	24.7%	3.4%	Kakara, Takashima, Kashiwajima, Ogawa, Madara
300–999	31	16,157	12.2%	4.8%	-
1,000–9,999	29	76,154	11.4%	22.5%	-
10,000 or more	9	231,370	3.5%	68.2%	-
Total	255	339,211	100.0%	100.0%	7 islands

The 255 islands by population size

Grouped by 2020 census population, the 255 islands covered by the Remote Islands Development Act include 33 islands with fewer than 10 people, 90 with 10–99, 63 with 100–299, 31 with 300–999, 29 with 1,000–9,999 and 9 with 10,000 or more (our calculation). 217 islands, or 85.1%, have fewer than 1,000 people, and the median island has 107. The nine islands with 10,000 or more people (Sado, Fukue, Tsushima, Tanegashima, Shodoshima, Iki, Nakadori, Dogo and Yakushima) hold 68.2% of the population of the 255 islands (MLIT).

All seven of Karatsu's islands have fewer than 300 people. Matsushima (45) and Mukushima (50) fall in the 10–99 group, and Kakara (117), Takashima (187), Kashiwajima (261), Ogawa (263) and Madara (280) in the 100–299 group (MLIT).

Prefecture	Islands	Population (2020)	Area (km²)
Hokkaido	6	9,819	416.74
Miyagi	7	594	12.59
Yamagata	1	158	2.73
Tokyo	9	21,532	290.51
Niigata	2	51,845	864.50
Ishikawa	1	66	0.55
Shizuoka	1	268	0.44
Aichi	3	3,430	3.44
Mie	6	2,861	13.69
Shiga	1	264	1.51
Hyogo	5	4,439	21.04
Shimane	4	19,122	342.62
Okayama	14	1,553	22.62
Hiroshima	13	9,398	65.17
Yamaguchi	21	2,755	64.41
Tokushima	2	193	2.09
Kagawa	24	31,510	217.56
Ehime	31	11,671	90.40
Kochi	2	142	11.33
Fukuoka	8	1,738	13.34
Saga	7	1,203	10.93
Nagasaki	51	113,056	1,550.36
Kumamoto	6	2,584	20.83
Oita	7	2,950	17.55
Miyazaki	3	721	5.19
Kagoshima	20	45,339	1,251.34
Total (26 prefectures)	255	339,211	5,313.48

Islands and population by prefecture

The 255 islands lie in 26 prefectures. Nagasaki has the most, with 51 islands, followed by Ehime (31), Kagawa (24), Yamaguchi (21) and Kagoshima (20). By population, Nagasaki has 113,056 people, Niigata 51,845 and Kagoshima 45,339. Saga has 7 islands with 1,203 people (MLIT).

Year	Designated remote islands	Amami Islands	Ogasawara Islands	Japan
1955	980,086	205,363	-	90,076,594
1960	940,230	196,483	-	94,301,623
1965	854,001	183,471	-	99,209,137
1970	753,265	164,114	782	104,665,171
1975	688,029	155,879	1,507	111,939,643
1980	653,764	156,074	1,879	117,060,396
1985	621,031	153,062	2,303	121,048,923
1990	570,017	142,834	2,361	123,611,167
1995	532,299	135,791	2,809	125,570,246
2000	494,676	132,315	2,824	126,925,843
2005	455,266	126,483	2,723	127,767,994
2010	414,532	118,773	2,785	128,057,352
2015	376,229	110,147	3,022	127,094,745
2020	339,280	104,281	2,929	126,146,099

Island population over time

The population of the areas covered by the Remote Islands Development Act was 980,086 in 1955, just after the act was passed, and 339,280 in 2020. Over the ten years from 2010 to 2020, the designated islands fell by 18.2%, Amami by 12.2%, depopulated areas by 15.7% and Japan by 1.5%, while Ogasawara grew by 5.2% (MLIT). In 2015, 39% of islanders were 65 or older, against 27% nationally (MLIT National Spatial Planning and Regional Policy Bureau).

The population of Okinawa's 38 designated islands rose by 0.1%, from 125,940 in 2015 to 126,103 in 2020 (Okinawa Prefecture).

Item	2013	2023	Change	Change in Japan
Elementary schools	288	267	−7.3%	−10.7%
Elementary pupils	16,989	13,863	−18.4%	−9.0%
Lower secondary schools	170	169	−0.6%	−6.4%
Lower secondary pupils	9,021	7,274	−19.4%	−9.7%
High schools	37	42	+13.5%	−3.9%
High school students	7,296	5,953	−18.4%	−11.8%
All schools	495	478	−3.4%	−8.5%
All pupils and students	33,306	27,090	−18.7%	−9.9%

Island schools and ferry routes across Japan

On the designated remote islands, elementary schools fell from 288 in 2013 to 267 in 2023 and their pupils from 16,989 to 13,863 (−18.4%). Lower secondary pupils fell from 9,021 to 7,274 (−19.4%). Over the same period, elementary pupils in Japan as a whole fell by 9.0% and lower secondary pupils by 9.7% (MLIT).

As of 1 April 2025, Japan had 272 remote island ferry routes linking the mainland and islands or islands with each other, 127 of them receiving national subsidies. 84 routes, or 30.9%, are in the area of the Kyushu District Transport Bureau (MLIT Kyushu District Transport Bureau). The ferries to Karatsu's seven islands are listed under "Ferries to the islands" below.

Item	Value	Source
Designated remote islands in Saga	The seven Genkai islands (all in Karatsu City)	Saga plan
Population of the seven islands	1,484 (2015) → 1,203 (2020), down 18.9%	Saga plan
Share aged 65+	54.1% (prefecture average 30.6%)	Saga plan (2020 census)
Distance from the mainland	0.6–8 km	Saga plan
Total area	10.96 km²	Saga and Karatsu plans

Saga Prefecture's remote islands

Saga Prefecture's Remote Island Development Plan (FY2023–FY2032) covers the seven Genkai islands of Karatsu City. They lie 0.6–8 km off the mainland, 40 km (Takashima) to 60 km (Madara) from central Fukuoka or Saga, and all are within Genkai Quasi-National Park. The plan's goal is to slow the population decline, which was 18.9% from 2015 to 2020 (Saga Prefecture).

Takashima187

Kashiwajima261

Ogawa Island263

Kakara Island117

Matsushima45

Madara Island280

Mukushima50

Island	Area	Population	Households	Aged 65+
Takashima	0.62 km²	187	98	62.0%
Kashiwajima	1.41 km²	261	130	64.4%
Ogawa Island	0.92 km²	263	125	55.1%
Kakara Island	2.84 km²	117	57	51.3%
Matsushima	0.63 km²	45	21	28.9%
Madara Island	4.24 km²	280	126	43.2%
Mukushima	0.30 km²	50	20	54.9%
Total	10.96 km²	1,203	577	54.1% (average)

Karatsu's seven inhabited islands

In the 2020 census the islands had: Madara 280, Ogawa 263, Kashiwajima 261, Takashima 187, Kakara 117, Mukushima 50 and Matsushima 45 people. The share aged 65+ ranges from 64.4% on Kashiwajima to 28.9% on Matsushima. There is no ferry between the islands, but the city's plan notes that the seven islands run joint community projects and their residents meet (Karatsu City).

Island	Route	Time	Sailings per day (each way)	Adult fare (one way)	Operator
Takashima	Karatsu (Chiyoda-machi) – Takashima	about 10 min	6	JPY 220	Saga Genkai Fisheries Cooperative
Kashiwajima	Minato – Kashiwajima	about 8 min	7	JPY 230	Karatsu Kisen Co.
Ogawa Island	Yobuko – Ogawa Island	about 20 min	4〜5	JPY 520	Kawaguchi Kisen
Kakara Island	Yobuko – Kakara Island	about 17 min	4	JPY 600	Kakarashima Kisen
Matsushima	Yobuko – Matsushima	about 15 min	3	JPY 460	Shinei Co.
Madara Island	Yobuko – Nagoya – Madara Island	50 min (8:10 from Yobuko, 9:00 at Madara; our calculation)	4	JPY 1,000	Yushomaru
Mukushima	Hoshika – Mukushima	about 10 min	3	JPY 460	Mukushima Kisen Co.

Route	Funding	Subsidy (JPY)	Passengers
Takashima	prefectural	58,131,351	111,548
Kashiwajima	national	50,267,395	59,760
Ogawa Island	national	11,448,050	54,784
Kakara Island	national	29,097,936	32,733
Matsushima	prefectural	50,987,677	5,373
Madara Island	national	35,607,420	34,593
Mukushima	prefectural	45,147,644	7,968
Total		280,687,473	306,759

Ferries to the islands

Each island has a regular ferry from the mainland, taking from about 8 minutes (Kashiwajima) to about 20 minutes (Ogawa). Madara is reached from Yobuko via Nagoya; the 8:10 sailing arrives at 9:00 (Karatsu City). In FY2025 Karatsu City spent JPY 299,101,473 (settled) on ferry operations. Passengers on the seven routes numbered 306,759, down 11,044 from 317,803; the city attributes this to fewer anglers and other visitors during the summer heat. 96% of planned sailings ran (Karatsu City).

School	FY2023	FY2024	FY2030 (projection)
Takashima Elementary	7	10	2
Madara Elementary	11	6	4
Kakara Elementary	5	8	4
Ogawa Elementary	10	7	3
Kakara Elementary, Matsushima branch	-	0	0
Irino Elementary, Mukushima branch	-	0	0

Island (type)	FY2024	FY2025
Takashima (dormitory, pupils only)	4	4
Kakara (with family)	2 families, 4	2 families, 3
Madara (with family)	1 family, 2	2 families, 4
Ogawa (with family)	2 families, 4	2 families, 5
Total	5 families, 14	6 families, 16

Island schools

On 1 May 2024 the island elementary schools had 10 (Takashima), 8 (Kakara), 7 (Ogawa) and 6 (Madara) pupils, and the Matsushima and Mukushima branch schools had none. The FY2030 projection is 2 to 4 pupils per school (Karatsu City). The Mukushima branch reopened in April 2026 with one pupil and one teacher, after 14 years, according to local news (Saga Television). Through the island study-abroad programme, 16 children from outside came to Takashima, Kakara, Madara and Ogawa in FY2025 (Karatsu City). At Takashima Elementary, where we ran workshops, there were 13 pupils in June 2026 and 14 in October (our records).

Island	Island community projects (JPY)	Fisheries revitalization grant (JPY)
Takashima	1,357,000	3,111,000
Kashiwajima	1,467,000	4,146,000
Ogawa Island	2,184,000	8,301,000
Kakara Island	2,111,000	2,067,000
Matsushima	1,277,000	1,380,000
Madara Island	1,842,000	6,742,000
Mukushima	552,000	2,421,000
Seven Islands Council	210,000	-
Total	11,000,000	28,168,000

Money Karatsu City spends on the islands

Of Karatsu City's FY2025 spending, island-by-island amounts are given for community projects (JPY 11,000,000 in total) and the fisheries revitalization grant (JPY 28,168,000). The fisheries grant supports seed release, removal of long-spined sea urchins, raising of red sea urchins and trial seaweed farming (Karatsu City). Nationally, MLIT's Remote Island Revitalization Grant supports settlement and exchange projects, such as island information and programmes to grow visitor and related populations. It covers up to 1/2 for prefectures and municipalities and up to 1/3 for private groups, paid through local governments (MLIT). The Fisheries Agency's remote island fisheries grant has a FY2026 budget of JPY 1,094 million (Fisheries Agency (posted on the MLIT website)).

Fiscal year	Marine litter collected in Japan
2020	27,740 t
2021	39,007 t
2022	54,264 t
2023	27,554 t
2024 (provisional)	39,551 t

Island (year)	What we recorded with the schools
Ogawa (FY2023)	23.07 kg of beach litter collected, of which 15.87 kg (about 69%) was plastic; presented by Ogawa Junior High students
Kakara (FY2024)	28 people collected 79.9 kg on 30 May. PET bottles by country: Japan 100, Korea 59, China 56, Malaysia 5, other 6
Madara (FY2025)	On 7 June, two light trucks of bulky waste and 34 bags of litter at Tajiri beach
Takashima (FY2026)	77 bottle caps picked up on 5 June. By country: Japan 45, Korea 13, China 9, other 10

Marine litter on the islands

Under the Marine Litter Disposal Promotion Act, the national government subsidizes the collection, disposal and prevention of marine litter by prefectures and municipalities, at 9/10 to 7/10, with higher rates for remote islands, depopulated areas and peninsulas (Ministry of the Environment). Japan collected 39,551 t of marine litter in FY2024 (provisional), 425 t of it in Saga (Cabinet Secretariat). Karatsu City's island plan states that ageing and population decline are making beach cleaning and collection on the islands difficult, and that the mainland coast faces the same problem (Karatsu City). In our beach cleanups with island schools, bottles and caps from Korea, China and elsewhere were found on both Kakara and Takashima (Karatsu Farm&Food (NPO)).

FAQ

Q1. How many islands does Japan have?

According to MLIT (as of 1 April 2026), Japan consists of 14,125 islands, of which 14,120 are remote islands and 417 are inhabited. 255 inhabited islands are covered by the Remote Islands Development Act.

Q2. How many people live on Karatsu's islands?

In the 2020 census, 1,203 people in 577 households lived on Takashima, Kashiwajima, Ogawa, Kakara, Matsushima, Madara and Mukushima, down 18.9% from 1,484 in 2015 (Saga Prefecture).

Q3. How do I get to Karatsu's islands?

All seven islands have regular ferries from the mainland, taking about 8 minutes (Kashiwajima) to about 20 minutes (Ogawa); Madara takes about 50 minutes from Yobuko via Nagoya. There are 3 to 7 sailings a day each way (Karatsu City timetables, checked 27 October 2026).

Q4. Where does the litter on the island beaches come from?

In our surveys with island schools, PET bottles collected on Kakara were Japan 100, Korea 59, China 56, Malaysia 5 and other 6; bottle caps on Takashima were Japan 45, Korea 13, China 9 and other 10.

Q5. Can children study on Karatsu's islands?

Yes. In FY2025, 16 children from outside studied on Takashima (dormitory) and on Kakara, Madara and Ogawa (with their families). Karatsu City spent JPY 13,467,770 on the programme.

Q6. Are Ogasawara, Amami and Okinawa covered by the Remote Islands Development Act?

No. The four Ogasawara islands, the eight Amami islands and the 38 designated islands of Okinawa each have their own law. The Remote Islands Development Act covers the other 255 islands (MLIT, as of 1 April 2026).

Q7. How many islands have very few people?

Of the 255 islands under the Remote Islands Development Act, 33 had fewer than 10 people and 90 had 10–99 in the 2020 census; 217 in total had fewer than 1,000 (our calculation from MLIT's list of designated areas).

Sources

Not covered on this page

We do not evaluate individual islands, groups or programmes, and we do not use values read from charts or figures we could not confirm in primary documents. Lower secondary pupil numbers (no recent public data found), fish catch (the prefecture and the city give different figures), visitor numbers, nuclear emergency plans, remote island ferry passengers nationwide (MLIT's published figures end in FY2021), marine litter by island nationwide (no national total by island was found) and population by island in Amami are not covered.

Citing this data, workshops, visits and island exchange

To cite the figures on this page, or to ask about workshops on your island or at your school, visits to the Karatsu islands, or exchange between islands, please see our Island ESD page, the contact page or write to info@karatsu-f-f.com.

About this page

Created by Hiroaki Kojima (Vice Director, Karatsu Farm&Food) / Contact: info@karatsu-f-f.com (contact page) / Published: 27 October 2026 / Markdown: island-data.md

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Related

▶ Karatsu Data Bank
▶ Island ESD: four islands off Karatsu
▶ Population and Migration in Numbers
▶ Seaweed Beds and Urchin Barrens in Numbers
▶ 離島の統計（日本語）