Oshima 渡島総合振興局

• Setting. Oshima fills the southern and central Oshima Peninsula in southwestern Hokkaido. Its coastline runs about 400 km, from Matsumae on the Sea of Japan, along the Tsugaru Strait and the Pacific, to Oshamambe at the head of Uchiura Bay (内浦湾, also called Funka Bay, 噴火湾)². Oshima borders Hiyama to the west, Shiribeshi to the north and Iburi to the northeast⁶.
• Capes and islands. Cape Shirakami (白神岬) in Matsumae is Hokkaido's southernmost cape, about 19.2 km from Cape Tappi in Aomori¹⁹. Cape Shiokubi (汐首岬), in the Toi district of Hakodate, is the point of Hokkaido nearest Honshu, about 17.5 km from Ōma²⁰. The islands of Ōshima (9.74 km²) and Kojima (1.54 km²) lie off Matsumae⁷.
• Mountains and volcanoes. The highest peaks are Yokotsu-dake (横津岳, 1,166.9 m), Hokkaido Komagatake (駒ヶ岳, 1,131.4 m) and Daisengen-dake (大千軒岳, 1,071.6 m)². Komagatake stands where Nanae, Shikabe and Mori meet²¹, and it is one of the volcanoes under continuous monitoring (常時観測火山)². In 1640 an eruption with a flank collapse set off a great tsunami that killed many people across Uchiura Bay in Iburi¹⁰.
• Lakes and rivers. The main lakes are Onuma (大沼, 5.30 km²), Konuma (小沼, 3.78 km²) and Junsainuma (蓴菜沼, 0.75 km²)². Onuma became a Hokkaido park in 1903. It was chosen as one of the "New Three Views of Japan" on 17 April 1915, and it became Japan's 13th quasi-national park in July 1958. Its name comes from the Ainu poro-to, "big lake"²². The largest river basins are the Yūrappu (遊楽部川, 351.8 km²), Shiriuchi (220.7 km²), Ōno (124.3 km²) and Oshamambe (112.0 km²)².
• Protected areas. Besides Onuma Quasi-National Park, Oshima has three prefectural natural parks: Matsumae-Yagoshi, Esan and Hiyama².
• Forest. Forests cover 312,934 ha, 5.7% of Hokkaido's forest land. Plantations are mainly todomatsu fir and sugi (Japanese cedar), a tree peculiar to southern Hokkaido and sold as "Dōnan sugi"²³.

Climate. By Hokkaido standards Oshima is mild, with a small temperature range and relatively little snow. Warm, moist air reaches the peninsula from both the Sea of Japan and the Pacific sides, so precipitation is fairly high². The southwest is warmest; the head of Funka Bay is colder and snowier. JMA normals for 1991–2020:

Prehistory

• The Kakinoshima (垣ノ島) and Ōfune (大船) sites in Hakodate are components of the World Heritage site "Jomon Prehistoric Sites in Northern Japan". The site has 17 components, six of them in Hokkaido, and the Washinoki stone circle (鷲ノ木) in Mori is one of its two associated sites²⁷. The site was inscribed on 27 July 2021¹.
• The hollow clay figure (中空土偶) found in Hakodate became a National Treasure in 2007. Grave goods from the Yunosato 4 site in Shiriuchi (1991) and finds from the Kotan Onsen site in Yakumo (1997) are Important Cultural Properties¹.

Medieval Wajin forts and Koshamain's War

• The twelve Wajin forts of southern Hokkaido (道南十二館) stretched along the coast from Shinori-date (志苔館) in Hakodate in the east to Hanazawa-date in Kaminokuni in the west. Their lords were vassals of the Andō clan²⁸.
• In 1456 a quarrel at a Wajin blacksmith's at Shinori, over a knife an Ainu man had ordered, ended with the smith killing him. The next year this set off Koshamain's War (コシャマインの戦い, 1457)²⁹. Ten of the twelve forts fell. In 1458 Takeda Nobuhiro killed Koshamain and his son²⁸.

The Matsumae domain

• In 1593 Kakizaki Yoshihiro was recognized by Toyotomi Hideyoshi as lord of Ezo, and the family went on to take the name Matsumae²⁸. A black-seal letter from Tokugawa Ieyasu in 1604 gave the Matsumae domain a monopoly on trade with the Ainu. Because rice could not be grown, the domain rewarded its retainers with trading rights instead of rice stipends. It divided the land into the Wajin area (和人地) in the south of the peninsula and Ezochi (蝦夷地) beyond. Matsumae's castle town passed 10,000 people by the early 1830s³⁰.
• During Shakushain's War in 1669, the Matsumae army set up its line at Kunnui (国縫), now part of Oshamambe³¹.
• The shogunate set up a magistrate at Hakodate in 1802. In 1807 it took the Matsumae lands under direct rule and moved the clan to Yanagawa in Mutsu, then restored them in 1821. In 1855, as Hakodate opened to foreign ships, the land east of Kikonai and north of Otobe again came under direct shogunate rule, guarded by the Matsumae, Nambu and Tsugaru domains¹⁰. The Hekirichi Jinya (Hokuto) and the Nambu outposts at Sawara (Mori) and Oshamambe are national historic sites from this period of coastal defense¹. Matsumae Castle is described as the last castle built in Japan in the traditional style³; see Matsumae for its history.

Treaty port and the Hakodate War

• Perry's squadron entered Hakodate in 1854. On 1 July 1859 Hakodate opened to foreign trade, together with Yokohama and Nagasaki, as one of Japan's first trade ports³². Goryokaku, where the Hakodate magistrate's office moved in 1864¹⁰, has been a Special Historic Site since 1952¹.
• In the Hakodate War (箱館戦争), about 3,000 former shogunate troops landed at Washinoki in present-day Mori on 4 December 1868. Their surrender on 27 June 1869 ended the Boshin War³³.

Meiji: from province to prefecture

• On 20 September 1869, Oshima Province (渡島国) was created with seven districts: Kameda, Kayabe, Kamiiso, Fukushima, Tsugaru, Nishi and Hiyama. The name comes from Watarishima, an old name for Hokkaido or for its gateway. The reading "Oshima" is what people from Nanbu and Tsugaru called the land¹⁰.
• The Kaitakushi (開拓使, colonization office) moved its headquarters from Hakodate to Sapporo in 1871. After the domains were abolished that year, the former Matsumae (Tate) domain became Tate Prefecture, which was merged that September into Hirosaki (later Aomori) Prefecture. Its four districts returned to the Kaitakushi in 1872. In 1881 the Tsugaru and Fukushima districts were merged into Matsumae District. In 1882 Hakodate Prefecture (函館県) was created when the Kaitakushi was abolished¹⁰.

The subprefecture

• 2 November 1897: subprefectures were set up at Hakodate, Kameda and Matsumae. In 1899 the Kameda and Hakodate offices were combined as Hakodate Subprefecture, and Matsumae was merged into it in 1903. On 17 August 1922 it was renamed Oshima Subprefecture (渡島支庁)¹¹.
• 1980: the combined population of today's 11 municipalities peaked at 517,383².
• March 1988: the Seikan Tunnel opened, linking Oshima to Aomori by rail³⁴.
• 2004–2006: a wave of municipal mergers left 2 cities and 9 towns²:
  • 1 December 2004: Hakodate absorbed Toi, Esan, Todohokke and Minamikayabe.
  • 1 April 2005: Mori and Sawara merged.
  • 1 October 2005: Yakumo merged with Kumaishi, which moved from Hiyama to Oshima.
  • 1 February 2006: Kamiiso and Ōno merged to form Hokuto.
• 2008–2010 reorganization: in June 2008 the Hokkaido Assembly passed an ordinance to regroup the 14 subprefectures into 9 regions. Under that plan, Hiyama was to be placed under a new "Dōnan General Subprefectural Bureau" (道南総合振興局). After protests from the subprefectures to be absorbed, the ordinance was amended on 31 March 2009. The "subprefectural bureaus" were given the same legal status as the general bureaus, and neighboring general bureaus could handle wide-area work for them. On 1 April 2010 Oshima Subprefecture became the Oshima General Subprefectural Bureau (渡島総合振興局), keeping its name and area¹¹. For duties best handled over a wide area, it serves all of Oshima and Hiyama⁶.
• 26 March 2016: the Hokkaido Shinkansen opened from Shin-Aomori to Shin-Hakodate-Hokuto⁵.

Fishing. Oshima faces three different seas: the Sea of Japan, the Tsugaru Strait and the Pacific (Funka Bay). In 2024 it landed about 123,000 t worth ¥34.0 billion, about 12% of Hokkaido's catch by both weight and value⁴:

• Scallops, mostly farmed, were the largest catch: 58,164 t, 47% of the weight, worth ¥11.34 billion. Scallop and kombu farming together made up more than half of the value.
• Kombu (kelp) was worth ¥7.16 billion, 41% of Hokkaido's kombu value.
• Yellowtail (buri) catches have grown. At 10,040 t, Oshima landed 61% of Hokkaido's yellowtail.
• Japanese flying squid (surume-ika) was worth ¥1.05 billion, 48% of Hokkaido's total.
• These figures exclude the Kumaishi district of Yakumo.

Farming. The bureau calls Oshima the birthplace of Hokkaido agriculture. Estimated farm output in 2023 was ¥46.5 billion³⁵:

• By value: other livestock, such as pigs, 29%; vegetables and fruit 27%; raw milk 17%; beef cattle 14%; rice and wheat 7%.
• Oshima leads Hokkaido in nira (Chinese chives) and long green onions. It is also a major grower of turnips, spinach and carnations (more than 100 varieties).
• Fukkurinko rice was bred in the region.
• Dairy farming is concentrated in the north, pigs on the Komagatake foothills, and beef cattle around Onuma and in the west. Brown Wagyu (褐毛和種) is sold as "Hakodate Wagyu".
• Farm numbers have fallen from 8,093 households in 1985 to 1,409 commercial farms in 2020. The two figures are counted differently.

Forestry. Sawmills shipped 36,000 m³ of lumber in FY2024. About 42% went outside Hokkaido, and for sugi cedar the share was about 60%. The region is building a "Dōnan sugi" brand²³.

Commerce and industry. In the 2021 Economic Census, businesses in Oshima sold ¥842.9 billion (4.9% of Hokkaido), 75.1% of it in Hakodate. Manufacturers shipped ¥363.1 billion (6.5% of Hokkaido): 49.7% from Hakodate, 19.4% from Hokuto and 11.1% from Mori³⁶. Fish processing and shipbuilding grew up on the old North Pacific fisheries and plentiful squid and pollock, but they are shrinking as fish stocks fall. Semiconductor makers and designers have gathered in the region. The sea off Matsumae was designated a promotion zone for offshore wind power in July 2025³⁶.

Tourism. Oshima had about 12.71 million visitors in FY2024, a record, and 12.82 million in FY2025. Of the FY2025 visitors, 4.09 million stayed overnight³⁷³⁸. Foreign overnight guests numbered 635,902 in FY2025, and 256,226 of them came from Taiwan³⁸. In FY2024, Hakodate drew 47.4% of the region's visitors and Nanae 16.9%. The bureau credits that year's record to a popular anime film set in Hakodate and more cruise-ship calls, and the rise in foreign overnight guests to flights from Taiwan and easier visas for Chinese visitors³⁷.

Regional specialties

Heritage. Oshima was the earliest part of Hokkaido to be developed, so it has many historic sites and cultural properties¹.

• Hokkaido Heritage. Seven of Hokkaido's 74 Hokkaido Heritage items are in Oshima⁴⁴:
  • Fukuyama (Matsumae) Castle and the temple quarter
  • the Jōmon sites along Uchiura Bay
  • the Shikabe geyser
  • Mount Hakodate and its fort ruins
  • Goryokaku and the remains of the Hakodate War
  • the streetcars
  • the townscape of Hakodate's Western District
• National designations include¹:
  • Hakodate's Motomachi–Suehirochō preservation district for groups of traditional buildings (1989)
  • the Old Public Hall of Hakodate Ward and the Hakodate Orthodox Church, both Important Cultural Properties
  • the Matsumae Castle main gate (1950)
  • the Matsumae family cemetery (1981)
  • the Washinoki site (2006)
• Matsumae Kagura (松前神楽). These Shinto dances became a national Important Intangible Folk Cultural Property on 8 March 2018¹. They are performed across southern Hokkaido; see Matsumae, Fukushima and Oshamambe.
• Kanchū Misogi (寒中みそぎ). This midwinter purification rite in Kikonai is a Hokkaido-designated intangible folk cultural property¹³. See Kikonai for how it is performed.

Festival calendar. These are the main events on the bureau's 2026 calendar (as of January 2026; events can change or be cancelled, so check first).

Ainu heritage

• Before and beside Wajin settlement. Place names across the region come from Ainu. Onuma is poro-to, "big lake"²², and in Yakumo Otoshibe, Nodaoi and Yūrap all have Ainu names⁴⁶. Most municipal names in Oshima come from, or translate, Ainu names. Hokuto, Yakumo and Fukushima are Japanese names; see each entry's name-origin section.
• Conflict and control. Koshamain's War (1457) began at Shinori in present-day Hakodate²⁹. Under the 1604 monopoly, the Matsumae domain gradually restricted the Ainu, who had once traded freely in the Wajin area and across the strait³⁰. In Shakushain's War (1669), Matsumae troops held the line at Kunnui in Oshamambe³¹. In 2016 Oshamambe put up a monument at the battlefield by the Kunnui River³¹.
• A boundary landscape. On the Sea of Japan coast the Wajin area reached as far as Kumaishi. The Pacific side was East Ezochi, and the Wajin area there was later pushed north to Yui in Yakumo. Two rare collections of southern Hokkaido Ainu objects come from Yakumo. The Shiiku collection from the Yūrap Ainu is in the Hakodate City Museum, and the Pirika-kai collection from the Otoshibe Ainu is held by the Matsumae Town Board of Education⁴⁶. Yakumo publishes this history on its "Ainu Mosir and the Two Seas" website⁴⁶.
• Museums. An Ainu household-goods collection (アイヌの生活用具コレクション) in Hakodate was designated a national Important Tangible Folk Cultural Property in 1959¹. See Hakodate for the Hakodate City Museum of Northern Peoples, and Oshamambe and Nanae for local Ainu history and programs. For hands-on Ainu culture, the national center, Upopoy, is in Shiraoi in Iburi.

• Hakodate. Its night view is sometimes called the world's best, and its treaty-port streets have a foreign air¹². There are also Goryokaku, Yunokawa Onsen and the morning market; see Hakodate.
• Onuma and Komagatake. Lakes, islets and a volcano in Nanae, a park since 1903²². The volcano is shared with Mori and Shikabe.
• Matsumae. Hokkaido's only castle town, with 10,000 cherry trees³. Nearby is Cape Shirakami, Hokkaido's southernmost cape¹⁹.
• Jōmon heritage. The National Treasure hollow clay figure is on show at the Hakodate Jomon Culture Center. The center is the main facility of the Jōmon Roman Minamikayabe roadside station, which bills itself as the only roadside station in Japan with a National Treasure⁴⁷. The Washinoki stone circle in Mori opens only on announced viewing days (see Mori).
• Hot springs and steam. You can watch the Shikabe geyser from a foot bath, which the station says is the only such place in Japan⁴⁸. Mori's Nigorikawa Onsen area is home to Hokkaido's largest geothermal power station¹⁵. See Hakodate for Yunokawa and Oshamambe for Futamata Radium Onsen.
• Tunnel and Shinkansen country. Watch trains at the Shinkansen observation tower in Shiriuchi¹³, and visit the Seikan Tunnel Memorial Hall and the yokozuna museum in Fukushima³.
• Wild coasts and crafts. Take a boat cruise along the Iwabe coast to the "Blue Cave" in Fukushima³. In Yakumo, the birthplace of Hokkaido's carved wooden bears, visit the Wood-Carved Bear Museum⁴⁹ and look over Funka Bay from Funkawan Panorama Park¹⁵. Check the Yakumo entry for current museum loans before you go.

Suggested routes

1. Hakodate and the Kameda Peninsula loop (2–3 days, by car). Spend a day or two in Hakodate, then follow National Route 278 east along the Tsugaru Strait:

   • Michi-no-Eki Natowa Esan and Mount Esan
   • the Jōmon Culture Center at Jōmon Roman Minamikayabe
   • the geyser in Shikabe

   Then climb inland to Onuma in Nanae, stop at Nanairo Nanae, and return to Hakodate on Route 5.

2. Shinkansen gateway to the castle town (1–2 days). Start at Shin-Hakodate-Hokuto in Hokuto (the Trappist Monastery and Hekirichi Jinya). Then follow Route 228 along the strait:

   • Kikonai: the Michi-no-Eki and Saraki Cape
   • Shiriuchi: the Seikan Tunnel portal and the Shinkansen tower
   • Fukushima: the yokozuna museum and the Iwabe cruise (29 April–12 October in 2026; book by the day before)⁵⁰
   • Matsumae: the castle, the temple quarter and the cherries

   Without a car, take the Shinkansen or the Dōnan Isaribi Railway to Kikonai, then a Hakodate Bus. From Matsumae the coast road continues north to Kaminokuni and Esashi in Hiyama.

3. Around Funka Bay on Route 5 (1–2 days). Travel north along the bay:

   • Onuma (Nanae)
   • Mori: ikameshi and cherries at YOU・遊・もり, with a detour along the Sawara coast to Tsudōru Plaza Sawara
   • Yakumo: the Wood-Carved Bear Museum and Funkawan Panorama Park. Route 277 crosses from here to Kumaishi on the Sea of Japan.
   • Oshamambe: kanimeshi and hot springs

   From Oshamambe, continue north to Kuromatsunai in Shiribeshi or east to Toyoura in Iburi.

Oshima has 10 Michi-no-Eki, in eight of its eleven municipalities. Hokuto, Yakumo and Oshamambe have none; see those entries for the nearest stops. The official Dōnan list also includes five stations in Hiyama⁵¹.

• Shinkansen. Shin-Hakodate-Hokuto (Hokuto) has been the Hokkaido terminus since 2016⁵:

  • The fastest train from Tokyo takes 3 hours 57 minutes, and from Shin-Aomori 57 minutes.
  • There are normally 10 round trips a day to Tokyo and one each to Shin-Aomori, Morioka and Sendai.
  • Eight round trips a day stop at Kikonai.

  Train times into Hakodate are in Hokuto and Hakodate.

• Shinkansen to Sapporo. The extension to Sapporo is about 212 km long, and about 80% of it is in tunnels. As of 1 February 2026, 90% of the tunneling had been dug. New stations are planned at Shin-Yakumo (tentative name) in Yakumo and at Oshamambe⁵. Opening was planned for the end of FY2030. A 2025 panel of the transport ministry estimated the end of FY2038 but said the date is still highly uncertain, and no new opening date has been set⁵⁷.

• Conventional rail. The Hokuto limited express links Hakodate and Sapporo in about 3.5 hours⁵⁸. Within Oshima it follows the Hakodate Main Line via Onuma, Mori, Yakumo and Oshamambe; see those entries for stops and times. The Dōnan Isaribi Railway took over the 37.8 km coastal line from Goryōkaku to Kikonai when the Shinkansen opened on 26 March 2016⁵⁹. Hakodate has a municipal tram network⁶.

• Air. Hakodate Airport handles about 1.8 million passengers a year (1,796,905 in 2024)⁶⁰:

  • Domestic routes: Haneda, Chūbu, Itami, New Chitose, Okadama and Okushiri. The airport's route map (as of July 2026) also shows Narita and notes that some routes are seasonal⁶¹.
  • International routes: Taipei (Taoyuan), and Seoul (Incheon), which was due to be suspended from 5 June 2026⁶⁰. The July 2026 route map shows only Taipei⁶¹.

  Flights from Haneda take about 1 hour 20 minutes, and the shuttle bus into Hakodate takes about 20 minutes⁵⁸.

• Sea. Hakodate is the region's major port⁶⁰:

  • Tsugaru Kaikyō Ferry and Seikan Ferry sail to Aomori, taking about 3 hours 40 minutes and about 4 hours. Tsugaru Kaikyō Ferry also sails to Ōma in about 1 hour 30 minutes⁵⁸.
  • A dedicated cruise-ship berth at Wakamatsu has been fully in use since FY2023⁶⁰.

• Roads. National Route 5 is the only trunk road linking southern and central Hokkaido. It is backed up by these roads⁶²:

  • the Dō-ō Expressway, which runs north from Nanae along Funka Bay
  • the Hakodate-Esashi Expressway, a national-highway motorway extended from Hokuto-Mohechi to Kikonai IC on 26 March 2022
  • the Hakodate Shindō bypass (20.2 km), from Hakodate to Nishi-Ōnuma in Nanae
  • the Hakodate New Outer Ring Road, open from Akagawa IC to Hakodate Airport IC since 28 March 2021

  A Matsumae Peninsula road from Kikonai to Matsumae is planned. From Sapporo it takes about 4 hours 20 minutes to drive to Hakodate, or about 5 hours to 6 hours 20 minutes by highway bus⁵⁸.

• Getting around. Outside Hakodate, a car is the easiest way to reach the coasts, onsen and lakes. Hakodate Bus serves the outlying towns; routes and times are in each municipality's entry. In winter the Funka Bay side is much snowier than the south: Oshamambe averages 600 cm of snowfall a season²⁶. Brown bears live across the region; see Fukushima for a recent fatal attack. Check local bear warnings before hiking or camping.