Ōzushima

, or Ozu Island, is an inhabited island in the Inland Sea, Japan. Administratively, it forms part of the city of Shūnan, Yamaguchi Prefecture. Ōzushima is also known as "Kaiten Island".

Geography

Situated in the Seto Inland Sea across the exit from Tokuyama Bay and formerly two islands, Ōzushima and are said to have become one some four hundred years ago. Gently curved, long, and thin, and with a outline that somewhat resembles a misshapen Y, today's Ōzushima extends some from north to south, and has an area of . There are a number of small settlements along the coast, including and , the centres for the island's masons and stoneworkers, the farming communities of and , and the fishing hamlets of and . Parks on the island include Ōzushima Park and Mashima Park, while part of the island and its surrounding waters is protected within Setonaikai National Park. The southern coastline is suffering from severe coastal erosion.

Flora

On Mashima, the southern end of the island, may be found a five-petalled variety of narcissus known as . Bulrushes (as featured in the myth of the Hare of Inaba) grow a short distance from Setohama port in paddies that were brought into cultivation during the Edo period but now lie abandoned, while at Amagaura there is a or celebrated old-growth tree, a ''Camellia japonica'' some three hundred years old, in height, and in circumference.

History

The name of the recently formed city of Shūnan, in which Ōzushima is located, is a portmanteau ( 周 南) that denote its situation in the south of old Suō Province. In early-modern times, Ōzushima formed part of (once territory owned by Tōdai-ji), a flourishing market town along the San'yōdō in Tokuyama Domain, the ''daimyō'' of which came from a branch of the Mōri clan, lords of Chōshū (or Hagi) Domain.

Like nearby , Ōzushima is a good source of high-grade granite, which was quarried for Ōsaka Castle: one block (whether cut for its original construction by Toyotomi Hideyoshi, as part of Mōri Terumoto's contribution, or for its rebuilding, by Tokugawa Hidetada after the Siege of Osaka, still lies on the island, in length, both in width and height, and weighing some .

In 1748, a ship from , an island in Hakata Bay, involved in the Kuroda Domain rice trade, and laden with rice, foundered off the island; ten bodies washed ashore and were buried on Ōzushima; five of their gravestones are inscribed, attesting to contact between the two sets of islanders—some of the stones were sent from Nokonoshima; the ten are honoured in an annual memorial service on the occasion of ''Tanabata''.

During the Great Pacific War, the island served as a testing and training base for the Imperial Japanese Navy's Special Attack submarine force, the ''Kaiten'' (manned torpedoes). With its origins as a testing range from 1938 for the Type 93 "oxygen torpedo", for construction of the ''Kaiten'' base, eight large caissons were towed over from Ōita Prefecture, the first in October 1943, the last in October 1944, with five further small caissons produced on Ōzushima. Opening in September 1944, this base was the first of what would be four such facilities (the others following in nearby Hikari, in November, and Hirao, in March, opening in what is now Hiji, Ōita Prefecture, in May 1945). Remains of the base on Ōzushima include a tunnel in length and in height, cut through the rock and used to transfer ''Kaiten'' by a rail tack to and from the maintenance area, maintenance facilities that extend from the port area of Mashima to the now closed Ōzushima Elementary School, an electricity transformer station, concrete bridges, staircases, an observation station on a rise overlooking the torpedo testing area, a firing test evaluation office, a storage facility for hazardous materials, kitchens, and barracks; there was also a seaplane hangar, while walls were built to keep out the islanders and maintain secrecy as to the operations within. As confirmed by base members and attested by archive materials, the ''Yamato'' could be seen clearly from the torpedo observation station at her final anchorage some off the southeast coast before departure on her final mission. Also on the island, and surviving in part, developed between November 1941 and May 1943 to protect Tokuyama Port and other nearby military facilities, on the summit of Mount Ōzu, the island's highest point, was an anti-aircraft battery, which in 1943 had five guns and a detail of fifty-four men.

In recognition of its historic significance, the Ōzushima Former Kaiten Firing and Training Base was in 2006 listed as a by the Japan Society of Civil Engineers. Also, it is due to this element of Ōzushima's past, commemorated at the Kaiten Memorial Museum, surrounded by cherries that flower and fall in the spring, that the island is sometimes referred to as "Kaiten Island".

Post-war and in recent decades, the demographic changes affecting the country have seen Ōzushima's population decline from a few thousand to a couple of hundred (269 in 2009, 227 in 2020), with many of those remaining of retirement age.

Intangible Heritage

* '' Heike Odori'' dances, performed for the souls of the vanquished Taira (Heike) clan, some of the survivors having settled on Ōzushima
* song: documentation and performance activities are being carried out by a preservation society
* , a pauper, but honest and with a strong faith, who poured himself into carving Buddhist statues, and thus at least became rich in merit (at the temple of in Motoura, to which he left all his worldly goods, a memorial service is still performed on the last day of Hōonkō)
* , the master mason, who, when the locals were at a quandary as to how best to go about transporting the stones for Ōsaka Castle, fanned them with his fan, at which point, as if rising up and floating, they spontaneously betook themselves to and piled themselves upon rafts along the shore (a small ''hokora'' shrine dedicated to Santarō remains to this day at Setohama)

Economy

Cultivation of tobacco and ''mikan'' was once widespread. Output now includes marine products, such as ''hijiki'' and ''wakame'' seaweed, sweet potatoes, and ''sake'' (marketed under the label ). There is also generally low-impact tourism: in 2006, following the release of Yokoyama Hideo's (filmed in part on Ōzushima and centred around the story of , who died when his submarine training vehicle accidentally sank, before washing ashore after the Surrender) nearly twenty-five thousand visited the island's Kaiten Memorial Museum, an increase of over sixty percent on the three years before.

''Meibutsu''

''Tokusanhin'' (a form of ''meibutsu'') include , a dish involving broiled carrot, ''gobō'' (burdock), and tōfu, seasoned with shōyu (Japanese soy sauce), that is said to have originated on Tsushima (Nagasaki Prefecture); and , which, despite the name, are made using the island's heritage sweet potatoes.

Transportation

There is a ferry link to on Honshū; this is serviced by the JR West-operated Tokuyama Station, on the San'yō Shinkansen and San'yō Main Lines. As of May 2020, there were two vessels and seven crossings a day.

Related maps and images

Series L571, U.S. Army Map Service, 1943 (Ōzushima).jpg, Composite of two US AMS 1943 maps, showing the location of "Ōtsu-shima", on the join a third from the right, across the mouth of Tokuyama Bay; the Kunisaki Peninsula in Ōita Prefecture is across the Inland Sea to the south
Series L775, U.S. Army Map Service, 1944 (Bofu Sheet 4449-3).jpg, 1944 US AMS map showing, to the bottom right, the northern half of "Ōtsu-shima"
Series L775, U.S. Army Map Service, 1944 (Oda Sheet 4448-4).jpg, 1944 US AMS map showing, to the top right, the southern half of "Ōtsu-shima"
Series L775, U.S. Army Map Service, 1945 (Tokuyama Sheet 4449-2).jpg, 1945 US AMS map showing, to the east of the previous pair and to the bottom left, Tokuyama and Tokuyama Wan (Bay)
Series L775, U.S. Army Map Service, 1946 (Murozumi Sheet 4448-1).jpg, 1946 US AMS map from the time of the Occupation showing, to the south of the previous map and to the top left, the tip of the southern arm of Tokuyama Bay and Sukumo-jima, a little to the east of Ōzushima
Map showing Ōzushima (Yamaguchi Prefectural Archives).jpg, Map dating to before the abolition of the ''han'' system and formerly owned by the Mōri clan, marked with and (Yamaguchi Prefectural Archives)
Shōhō Kuniezu - Suō Province (Yamaguchi Prefectural Archives).jpg, '' Shōhō Kuniezu'' - Suō Province, showing water between Ōzushima and Mashima (Yamaguchi Prefectural Archives)
Genroku Kuniezu - Suō Province (Yamaguchi Prefectural Archives).jpg, ''Genroku Kuniezu'' - Suō Province, with Nagato in red, Iwami in green, and Aki in pink (Yamaguchi Prefectural Archives)
Tenpō Kuniezu - Suō Province (Yamaguchi Prefectural Archives).jpg, '' Tenpō Kuniezu'' - Suō Province (Yamaguchi Prefectural Archives)
Ohzushima01.jpg, View from Ōzushima Port, with a sign saying "Welcome to Kaiten Island, Ōzushima''"
Gyoraitunnel01.jpg, Tunnel from the days of the ''Kaiten'' training base
Kaitenkinenkan01.jpg, The approach to Kaiten Memorial Museum
Yamato (1945-04-06 09-47)1.jpg, The ''Yamato'' at 09:47 on 6 April 1945, hours before departing on her final mission; Mashima can be seen above to the left
Yamato (1945-04-06 09-47)2.jpg, Magnification of the previous image
Yamato (1945-04-06 09-47)3.jpg, Magnification of the previous image

See also

* Setonaikai National Park
* Etajima, Ōkunoshima, Hashima
* Yasukuni Jinja Yūshūkan
* Chiran Peace Museum for Kamikaze Pilots
* Noshima

References

External links

*
Japan's outlying islands
(MLIT)
*
Basic map of Ōzushima's sites
( Shūnan City)
*
Map and images of the island's Kaiten-related facilities
( Shūnan City)
*
Detailed maps of Setonaikai National Park
( Ministry of the Environment; Ōzushima to the top left of 山口県･福岡県地域（西部）)

{{DEFAULTSORT:Ozushima
Shūnan, Yamaguchi
Islands of the Seto Inland Sea
Islands of Yamaguchi Prefecture