Kuril Islands in the context of "Sea of Okhotsk"

The Japanese archipelago (Japanese: 日本列島, Hepburn: Nippon/Nihon Rettō; Japanese pronunciation: [ɲip.pon/ɲi.hon ɾeꜜt.toː]) is an archipelago of 14,125 islands that form the country of Japan. It extends over 3,000 km (1,900 mi) from the Sea of Okhotsk in the northeast to the East China and Philippine seas in the southwest along the Pacific coast of the Eurasian continent, and consists of three island arcs from north to south: the Northeastern Japan Arc, the Southwestern Japan Arc, and the Ryukyu Island Arc. The Daitō Islands, the Izu–Bonin–Mariana Arc, and the Kuril Islands neighbor the archipelago.

Japan is the largest island country in East Asia and the fourth-largest island country in the world with 377,975.24 km (145,937.06 sq mi). It has an exclusive economic zone of 4,470,000 km (1,730,000 sq mi).

The Empire of Japan, also known as the Japanese Empire or Imperial Japan, was the Japanese nation state that existed from the Meiji Restoration on January 3, 1868, until the Constitution of Japan took effect on May 3, 1947. From August 1910 to September 1945, it included the Japanese archipelago, the Kurils, Karafuto, Korea, and Taiwan. The South Seas Mandate and concessions such as the Kwantung Leased Territory were de jure not internal parts of the empire but dependent territories. In the closing stages of World War II, with Japan defeated alongside the rest of the Axis powers, the formalized surrender was issued on September 2, 1945, in compliance with the Potsdam Declaration of the Allies, and the empire's territory subsequently shrunk to cover only the Japanese archipelago resembling modern Japan.

Under the slogans of "Enrich the Country, Strengthen the Armed Forces" and "Promote Industry" which followed the Boshin War and the restoration of power to the emperor from the shogun, Japan underwent a period of large-scale industrialization and militarization, often regarded as the fastest modernization of any country to date. All of these aspects contributed to Japan's emergence as a great power following the First Sino-Japanese War, the Boxer Rebellion, the Russo-Japanese War, and World War I. Economic and political turmoil in the 1920s, including the Great Depression, led to the rise of militarism, nationalism, statism and authoritarianism, during which Japan joined the Axis alliance with Nazi Germany and Fascist Italy, conquering a large part of the Asia–Pacific; during this period, the Imperial Japanese Army (IJA) and the Imperial Japanese Navy (IJN) committed numerous atrocities and war crimes, including the Nanjing Massacre. There has been a debate over defining the political system of Japan as a dictatorship, which has been disputed due by the absence of a dictator, and over calling it fascist. The other suggested terms were para-fascism, militarism, corporatism, totalitarianism, and police state.

Hokkaido (Japanese: 北海道, Hepburn: Hokkaidō; pronounced [hok.kaꜜi.doː] , lit. 'Northern Sea Circuit'; Ainu: Aynu Mosir, lit. 'Land of the Ainu') is the second-largest and northernmost of Japan's four main islands. Together with its surrounding islands, it comprises the largest and northernmost prefecture, making up its own region. The Tsugaru Strait separates Hokkaidō from Honshu. The two islands are connected by railway via the Seikan Tunnel.

The largest city on Hokkaido is its capital, Sapporo, which is also its only ordinance-designated city. Sakhalin lies about 43 kilometres (27 mi) to the north of Hokkaidō. To the east and northeast are the Kuril Islands, which are administered by Russia. The four most southerly are claimed by Japan. Hokkaido's position on the northern end of the Japanese archipelago results in a colder climate, with the island seeing significant snowfall each winter. Despite the harsher climate, it serves as an agricultural breadbasket for many crops.

North Asia or Northern Asia (Russian: Северная Азия) is the northern region of Asia, which is defined in geographical terms and consists of three federal districts of Russia: Ural, Siberian, and the Far Eastern. North Asia is bordered by the Arctic Ocean to its north; by Eastern Europe to its west; by Central Asia and East Asia to its south; and by the Pacific Ocean and Northern America to its east. It covers an area of 13,100,000 square kilometres (5,100,000 sq mi), or 8.8% of Earth's total land area; and is the largest subregion of Asia by area, occupying approx. 29.4% of Asia's land area, but is also the least populated, with a population of around 37 million, accounting for merely 0.74% of Asia's population.

Topographically, the region is dominated by the Eurasian Plate, except for its eastern part, which lies on the North American, Amurian, and Okhotsk Plates. It is divided by three major plains: the West Siberian Plain, Central Siberian Plateau, and Verhoyansk-Chukotka collision zone. The Uralian orogeny in the west raised Ural Mountains, the informal boundary between Asia and Europe. Tectonic and volcanic activities are frequently occurred in the eastern part of the region as part of the Ring of Fire, evidenced by the formation of island arcs such as the Kuril Islands and ultra-prominent peaks such as Klyuchevskaya Sopka, Kronotsky, and Koryaksky. The central part of North Asia is a large igneous province called the Siberian Traps, formed by a massive eruption which occurred 250 million years ago. The formation of the traps coincided with the Permian–Triassic extinction event.

The Northeastern Japan Arc, also Northeastern Honshū Arc, is an island arc on the Pacific Ring of Fire. The arc runs north to south along the Tōhoku region of Honshū, Japan. It is the result of the subduction of the Pacific plate underneath the Okhotsk plate at the Japan Trench. The southern end of the arc converges with the Southwestern Japan Arc and the Izu–Bonin–Mariana Arc at the Fossa Magna (ja) at the east end of the Itoigawa-Shizuoka Tectonic Line (ITIL). This is the geologic border between eastern and western Honshū. Mount Fuji is at the point where these three arcs meet. To the north, the Northeastern Japan arc extends through the Oshima Peninsula of Hokkaidō. The arc converges in a collision zone with the Sakhalin Island Arc and the Kuril Island Arc in the volcanic Ishikari Mountains of central Hokkaidō. This collision formed the Teshio and Yūbari Mountains.

The Ōu Mountains form the backbone of the volcanic part of the inner arc that run from Natsudomari Peninsula in Aomori Prefecture south to Mount Nikkō-Shirane in Tochigi and Gunma prefectures. The volcanic front consists of four north to south lines of Quaternary volcanoes and calderas, which extend the length of the range. It also includes the Quaternary volcanoes of southwestern Hokkaido. The Dewa Mountains and the Iide Mountains are non-volcanic uplift ranges that run parallel to the west of the Ōu Mountains.

The surrender of the Empire of Japan in World War II was announced by Emperor Hirohito on 15 August and formally signed on 2 September 1945, ending the war. By the end of July 1945, the Imperial Japanese Navy (IJN) was incapable of conducting major operations and an Allied invasion of Japan was imminent. Together with the United Kingdom and China, the United States called for the unconditional surrender of Japan in the Potsdam Declaration on 26 July 1945—the alternative being "prompt and utter destruction". While publicly stating their intent to fight on to the bitter end, Japan's leaders (the Supreme Council for the Direction of the War, also known as the "Big Six") were privately making entreaties to the publicly neutral Soviet Union to mediate peace on terms more favorable to the Japanese. While maintaining a sufficient level of diplomatic engagement with the Japanese to give them the impression they might be willing to mediate, the Soviets were covertly preparing to attack Japanese forces in Manchuria and Korea (in addition to South Sakhalin and the Kuril Islands) in fulfillment of promises they had secretly made to the US and the UK at the Tehran and Yalta Conferences.

On 6 August 1945, at 8:15 am local time, the United States detonated an atomic bomb over the Japanese city of Hiroshima. Sixteen hours later, American president Harry S. Truman called again for Japan's surrender, warning them to "expect a rain of ruin from the air, the like of which has never been seen on this earth." Late on 8 August 1945, in accordance with the Yalta agreements, but in violation of the Soviet–Japanese Neutrality Pact, the Soviet Union declared war on Japan, and soon after midnight on 9 August 1945, the Soviet Union invaded the Japanese puppet state of Manchukuo. Hours later, the U.S. dropped a second atomic bomb on the Japanese city of Nagasaki.

Ainu (アイヌ イタㇰ, aynu itak), or more precisely Hokkaido Ainu (Japanese: 北海道アイヌ語), is the native language of the Ainu people on the northern Japanese island of Hokkaido. It is a member of the Ainu language family, itself considered a language family isolate with no academic consensus regarding its origin. Until the 20th century, the Ainu languages – Hokkaido Ainu, Kuril Ainu, and Sakhalin Ainu – were spoken throughout Hokkaido, the southern half of the island of Sakhalin and by small communities in the Kuril Islands, up to the southern tip of Kamchatka.

Following the colonization of Hokkaido, the number of Hokkaido Ainu speakers declined steadily throughout the 20th century. By 2008, Hokkaido Ainu was critically endangered, with only two elderly people reported to speak it as their first language. According to the linguist Hiroshi Nakagawa, by 2021 no one in Japan had Ainu as their first language.