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The Kantō Plain (Japanese: 関東平野, Hepburn: Kantō heiya), in the Kantō region of central Honshu, is the largest plain in Japan. Its 17,000 km covers more than half of the region extending over Tokyo, Saitama Prefecture, Kanagawa Prefecture, Chiba Prefecture, Gunma Prefecture, Tochigi Prefecture, and Ibaraki Prefecture.
Operation Downfall was the proposed plan by United States and British Commonwealth forces for the invasion of the Japanese home islands near the end of World War II. It was canceled when Japan surrendered following the atomic bombings of Hiroshima and Nagasaki, the Soviet declaration of war, and the invasion of Manchuria.
The operation had two parts: Operation Olympic and Operation Coronet. Set to begin in November 1945, Operation Olympic was intended to capture the southern third of the southernmost main Japanese island, Kyūshū, with the recently captured island of Okinawa to be used as a staging area. In early 1946 would come Operation Coronet, the planned invasion of the Kantō Plain, near Tokyo, on the main Japanese island of Honshu. Airbases on Kyūshū captured in Operation Olympic would allow land-based air support for Operation Coronet. If Downfall had taken place, it would have been the largest amphibious operation in history, surpassing D-Day.
The Kantō region (関東地方, Kantō Chihō; IPA: [kaꜜn.toː, kan.toː tɕiꜜ.hoː, kan.toː tɕi̥.hoꜜː]) is a geographical region of Honshu, the largest island of Japan. In a common definition, the region includes the Greater Tokyo Area and encompasses seven prefectures: Chiba, Gunma, Ibaraki, Kanagawa, Saitama, Tochigi, and Tokyo. Slightly more than 45 percent of the land area within its boundaries is the Kantō Plain. The rest consists of the hills and mountains that form land borders with other regions of Japan.
As the Kantō region contains Tokyo, the capital and largest city of Japan, the region is considered the center of Japan's politics and economy. According to the official census on October 1, 2010, by the Statistics Bureau of Japan, the population was 42,607,376, amounting to approximately one third of the total population of Japan.
Honshu (Japanese: 本州, Hepburn: Honshū; pronounced [hoꜜɰ̃.ɕɯː] ; lit. 'main province'), historically known as Akitsushima (秋津島; lit. 'dragonfly island'), is the largest of Japan's four main islands. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the seventh-largest island in the world, and the second-most populous after the Indonesian island of Java.
Honshu had a population of 104 million as of 2017, constituting 81.3% of the entire population of Japan, and mostly concentrated in the coastal areas and plains. Approximately 30% of the total population resides in the Greater Tokyo Area on the Kantō Plain. As the historical center of Japanese cultural and political power, the island includes several past Japanese capitals, including Kyoto, Nara, and Kamakura. Much of the island's southern shore forms part of the Taiheiyō Belt, a megalopolis that spans several of the Japanese islands. Honshu also contains Japan's highest mountain, Mount Fuji, and its largest lake, Lake Biwa.
Gunma Prefecture (群馬県, Gunma-ken; Japanese pronunciation: [ɡɯꜜm.ma, ɡɯm.maꜜ.keɴ]) is a landlocked prefecture of Japan located in the Kantō region of Honshu. Gunma Prefecture has a population of 1,937,626 (1 October 2019) and has a geographic area of 6,362 square kilometres (2,456 sq mi). Gunma Prefecture borders Niigata Prefecture and Fukushima Prefecture to the north, Nagano Prefecture to the southwest, Saitama Prefecture to the south, and Tochigi Prefecture to the east.
Maebashi is the capital and Takasaki is the largest city of Gunma Prefecture, with other major cities including Ōta, Isesaki, and Kiryū. Gunma Prefecture is one of only eight landlocked prefectures, located on the northwestern corner of the Kantō Plain with 14% of its total land being designated as natural parks.
The Taiheiyō Belt (Japanese: 太平洋ベルト, Hepburn: Taiheiyō Beruto; lit. "Pacific Belt"), also known as the Tōkaidō corridor, is the megalopolis in Japan extending from Ibaraki Prefecture in the northeast to Fukuoka Prefecture in the southwest, running for almost 1,200 km (750 mi). Its estimated population as of 2011 was about 80 million.
The urbanization zone runs mainly along the Pacific coast (hence the name) of Japan from Kantō region to Osaka, and the Inland Sea (on both sides) to Fukuoka, and is concentrated along the Tōkaidō–Sanyō rail corridor. A view of Japan at night clearly shows a rather dense and continuous strip of light (demarcating urban zones) that delineates the region. The high population is particularly due to the large plains – the Kantō Plain, Kinai Plain, and Nōbi Plain – which facilitate building in otherwise mountainous Japan.
The Great Kantō Earthquake (Japanese: 関東大地震, romanized: Kantō daijishin or 関東大震災, Kantō daishinsai) was a megathrust earthquake that struck the Kantō Plain on the main Japanese island of Honshu at 11:58:32 JST (02:58:32 UTC) on Saturday, 1 September 1923. It had an approximate magnitude of 8.0 on the moment magnitude scale (Mw), with its epicenter located some 100 km (62 mi) southwest of the capital Tokyo. The earthquake devastated Tokyo, the port city of Yokohama, and surrounding prefectures of Kanagawa, Chiba, and Shizuoka, and caused widespread damage throughout the Kantō region.
The event was a complex disaster, with modern research indicating it consisted of three consecutive shocks in the span of several minutes. The initial megathrust event in Kanagawa Prefecture was followed three minutes later by a magnitude 7.2 earthquake centered beneath Tokyo Bay, and two minutes after that by a magnitude 7.3 shock in Yamanashi Prefecture. Fires, exacerbated by strong winds from a nearby typhoon, spread rapidly through the densely populated urban areas, accounting for the majority of the devastation and casualties. The death toll is estimated to have been between 105,000 and 140,000 people, including tens of thousands who went missing and were presumed dead. Over half of Tokyo and nearly all of Yokohama were destroyed, leaving approximately 2.5 million people homeless. The disaster triggered widespread social unrest, including the Kantō Massacre, in which ethnic Koreans and others mistaken for them were murdered by vigilante groups based on false rumors.