is a

volcanic A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often fo ...

Japanese island in the

Philippine Sea The Philippine Sea is a List of seas#Marginal seas by ocean, marginal sea of the Pacific Ocean, Western Pacific Ocean east of the list of islands of the Philippines, Philippine Archipelago (hence the name) and the List of seas#Largest seas ...

. Nussbaum, Louis-Frédéric. (2005)
"''Izu Shotō'',"
''Japan Encyclopedia,'' p. 412. The island is administered by

Tōkyō Tokyo, officially the Tokyo Metropolis, is the capital and most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is one of the most populous urban areas in the world. The Greater Tokyo Area, which ...

and is located approximately northwest of the

Miyake-jima is a Volcano, volcanic island in the Izu Islands, Izu archipelago in the Philippine Sea approximately southeast of Tokyo, Japan. As with the other islands in the Izu Island group, Miyake-jima forms part of the Fuji-Hakone-Izu National Park. ...

and southwest of the

Nii-jima is a volcano, volcanic Islands of Japan, Japanese island administered by the Tokyo Metropolitan Government. It is one of the Izu Seven Islands, group of the seven northern islands of the Izu Islands, Izu archipelago, and is located approximate ...

. It is one of the Izu Seven Islands, a group of the seven northern islands of the Izu archipelago. Kōzushima is administratively part of Kōzushima Village (founded 1923), under Ōshima Subprefecture of Tokyo Metropolis. , the island's population was 1,952. Kōzushima is within the boundaries of the

Fuji-Hakone-Izu National Park is a national park in Yamanashi, Shizuoka, and Kanagawa Prefectures, and western Tokyo Metropolis, Japan. It consists of Mount Fuji, Fuji Five Lakes, Hakone, the Izu Peninsula, and the Izu Islands. Fuji-Hakone-Izu National Park covers . Rat ...

Geology

Kōzu-shima is a compound volcanic island 6 km in length with a maximum width of 4 km. The island is formed from a cluster of eighteen

lava dome In volcanology, a lava dome is a circular, mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions ...

s, with

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture (geology), texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained matri ...

and pyroclastic ash deposits. The highest of these lava domes, , has a height of , and was last active in 838 AD per the ancient Japanese history Shoku Nihon Kōki. Compared with most of the other islands in the Izu archipelago, Kōzu-shima is relatively flat, with small eroded hills, and lacks the high coastal cliffs found on the other islands. Earthquake swarms have occurred at Kōzu-shima during the 20th century.

Climate

Important Bird Area

The island has been recognised as an

Important Bird Area An Important Bird and Biodiversity Area (IBA) is an area identified using an internationally agreed set of criteria as being globally important for the conservation of bird populations. IBA was developed and sites are identified by BirdLife Int ...

(IBA) by

BirdLife International BirdLife International is a global partnership of non-governmental organizations that strives to conserve birds and their habitats. BirdLife International's priorities include preventing extinction of bird species, identifying and safeguarding i ...

because it supports populations of

Japanese wood pigeon The black wood pigeon or Japanese wood pigeon (''Columba janthina'') is a species of bird in the family Columbidae. It is found in East Asia along shorelines of the Pacific's Korea Strait, Philippine Sea and East China Sea. It is believed to be ...

s, Tristram's storm petrels,

Japanese murrelet The Japanese murrelet or crested murrelet (''Synthliboramphus wumizusume'') is a small seabird in the auk family that occurs along the remote rocky coasts and in the offshore waters of Japan, and may also be found after the breeding season as far ...

s, Ijima's leaf-warblers,

Pleske's grasshopper warbler Styan's grasshopper warbler (''Helopsaltes pleskei''), also known as Pleske's grasshopper warbler and Taczanowski's warbler, is a species of Old World warbler in the family Locustellidae. It breeds in eastern Siberia to Korea, Kyushu and Izu Isl ...

s and

Izu thrush The Izu thrush or Izu Islands thrush (''Turdus celaenops'') is a bird of the thrush family native to Japan. Behavior Feeding Izu thrushes eat small animals, such as earthworms and insects, and fruits, like cherries or mullberries. Breeding Th ...

es.

History

Kōzu-shima has been inhabited since at least the

Japanese Paleolithic The is the period of human inhabitation in Japan predating the development of pottery, generally before 10,000 BC. The starting dates commonly given to this period are from around 40,000 BC, with recent authors suggesting that there is good evi ...

era, and archaeologists have found

Jōmon period In Japanese history, the is the time between , during which Japan was inhabited by the Jōmon people, a diverse hunter-gatherer and early agriculturalist population united by a common culture, which reached a considerable degree of sedentism an ...

stone tools made from

obsidian Obsidian ( ) is a naturally occurring volcanic glass formed when lava extrusive rock, extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. Produced from felsic lava, obsidian is rich in the lighter element ...

in Shizuoka and

Yamanashi Prefecture is a prefecture of Japan located in the Chūbu region of Honshu. Yamanashi Prefecture has a population of 787,592 (1 February 2025) and has a geographic area of 4,465 km2 (1,724 sq mi). Yamanashi Prefecture borders Saitama Prefecture to the n ...

s. Under the

Ritsuryō is the historical Japanese legal system, legal system based on the philosophies of Confucianism and Legalism (Chinese philosophy), Chinese Legalism in Feudal Japan. The political system in accord to Ritsuryō is called "Ritsuryō-sei" (). ''Kya ...

system of the early

Nara period The of the history of Japan covers the years from 710 to 794. Empress Genmei established the capital of Heijō-kyō (present-day Nara). Except for a five-year period (740–745), when the capital was briefly moved again, it remained the capita ...

, the island was part of

Suruga Province was an Provinces of Japan, old province in the area that is today the central part of Shizuoka Prefecture. Suruga bordered on Izu Province, Izu, Kai Province, Kai, Sagami Province, Sagami, Shinano Province, Shinano, and Tōtōmi Province, Tōtōm ...

. It was transferred to

Izu Province was a province of Japan in the area now part of Shizuoka Prefecture and Tokyo. Nussbaum, Louis-Frédéric. (2005). "''Izu''" in . Izu bordered on Sagami and Suruga Provinces. Its abbreviated form name was . The mainland portion of Izu Prov ...

when Izu separated from Suruga in 680 AD. During the

Heian period The is the last division of classical Japanese history, running from 794 to 1185. It followed the Nara period, beginning when the 50th emperor, Emperor Kammu, moved the capital of Japan to Heian-kyō (modern Kyoto). means in Japanese. It is a ...

, obsidian was the primary export from the island.

In popular culture

The island is the hometown of the idol duet Sunny Passion in the franchise Love Live! Superstar!!. Several episodes of the corresponding anime TV series take place there. In the film

Weathering with You is a 2019 Japanese animated romantic fantasy film written and directed by Makoto Shinkai, produced by CoMix Wave Films and distributed by Toho. It follows a 16-year-old high school boy, Hodaka Morishima, who runs away from his troubled rur ...

, Hodaka Morishima (the male protagonist) is from the island.

Notes

References

* ''Teikoku's Complete Atlas of Japan'', Teikoku-Shoin., Ltd. Tokyo 1990,

External links

Kozushima Village Official Website

- Japan Meteorological Agency * - Japan Meteorological Agency

- Geological Survey of Japan * {{DEFAULTSORT:Kozushima Izu Islands Active volcanoes Islands of Tokyo Important Bird Areas of the Nanpo Islands Seabird colonies VEI-4 volcanoes