Over a third of Japan's population lives in the Kantō region
The Kantō region on Honshu holds Tokyo and six surrounding prefectures, and the October 2025 census counted 43,509,179 people there, more than one in three Japanese residents. Much of it sits on Japan's largest plain, ringed by mountains and facing an ocean trench behind two major earthquakes.
Kantō is usually defined as Tokyo plus Chiba, Gunma, Ibaraki, Kanagawa, Saitama and Tochigi, covering the Greater Tokyo Area. Because the capital lies here, the region is treated as the political and economic heart of the country. Its boundaries shift depending on who is drawing them, though. The regional governors' association also brings in Yamanashi, Nagano and Shizuoka, while the national trade and industry bureau for Kantō covers eleven prefectures, adding Niigata as well. Oddly, Tokyo's own police sit outside the national police region for Kantō and liaise with the national agency through a separate office.
Just over 45 percent of the land is the Kantō Plain, built from young river sediments; hills and mountains make up the rest and form the borders with neighbouring regions. Rivers such as the Arakawa and Edo drain into Tokyo Bay, while the Tone and Kinugawa reach the Pacific near Inubōsaki. Tokyo Bay, enclosed by the Boso and Miura peninsulas, is lined with industry. To the south, Sagami Bay is crossed by the Sagami Trough, the source of both Kantō earthquakes, and communities across the region invest in earthquake safety.
The slopes show clear bands of vegetation. Evergreen broad-leaved laurel forest covers low mountains up to somewhere between 500 and 900 metres depending on the range, reaching highest in Hakone. Above it grow deciduous woods of beech, birch and oak, and higher still conifers such as Veitch's fir. Nasuno, at the foot of the northern mountains, is Japan's biggest alluvial fan.
The region's summit is Mount Nikko-Shirane on the Tochigi and Gunma border, the loftiest peak anywhere north of Kantō. Prefectural high points vary enormously: Saitama's Mount Sanpo reaches 2,483 metres and Tokyo's Mount Kumotori 2,017, while Chiba's highest ground, Mount Atago, manages only 408 metres, the lowest top point of any prefecture in the region.
Source: Kantō region
