What is Japan’s ‘flattest’ prefecture?

View from Minami Bōsō Quasi-National Park from Wikipedia.

Seventy-five percent of Japan’s land area is mountainous and even parts of the country that we consider relatively flat, like Tokyo, have tall mountains.

(The highest point in Tokyo is the peak of Mount Kumotori (雲取山), a 2,017-meter mountain that stands on its boundary with Saitama and Yamanashi Prefectures.)

In a country where prefectures and regions are bounded by mountain ranges, Japan’s flattest prefecture is separated from its neighbors by bodies of water, not mountainous peaks. In the country of Mount Fuji and the 3,000-meter mountains of central Honshū, this prefecture is so flat its highest point, Mount Atago (愛宕山), is a 408-meter dwarf, shorter than the Sky Tree.

So which prefecture is it?

If you guessed “Okinawa,” you wouldn’t be far off the mark. But even Okinawa’s diminutive 526-meter Mount Omoto is just a little bit taller than Mount Atago of Chiba Prefecture, which claims the title of Japan’s “flattest prefecture.” (See the list of highest mountains by prefecture below.)

Chiba, the land of a thousand leaves and Japan’s flattest prefecture

For people living in the Greater Tokyo Area, Chiba Prefecture (千葉県) is mostly associated with Tokyo Disney Resort located in Urayasu City and Narita International Airport located in the Narita City.

It borders Ibaraki Prefecture (茨城県) to the north by the Tone River and Saitama Prefecture (埼玉県) and Tokyo to the west by the smaller Edo River. That’s as flat a boundary as you can get.

It is also part of the great Kantō Plane, the widest flat land in the whole of Japan.

Relief map of Chiba Prefecture and surrounding areas of the Kantō region from Google Maps.

On the map above, Tokyo and Saitama appear flatter, but are actually quite mountanous on their westernmost parts, while Chiba is uniformly flat with some hilly areas on the lower part of the peninsula.

No worries about accidentally bumping into mountains for airplanes landing on Narita International Airport.

Highest mountains in each prefecture in Japan

Many prefectures are separated by mountains and mountain ranges. For example, Mount Fuji is shared by Shizuoka and Yamanashi Prefectures, and Tochigi and Gunma share Mount Nikkō-Shirane, a volcano in the Nikkō National Park.

Prefecture Mountain Elevation (m)
Chiba Mount Atago 408
Okinawa Mount Omoto 526
Osaka Mount Yamato Katsuragi 959
Kyoto Mount Minago 972
Ibaraki Mount Yamizo 1,022
Kagawa Mount Ryūō 1,060
Saga Mount Kyōgatake 1,076
Fukuoka Mount Shakagatake 1,230
Yamaguchi Mount Jakuchi 1,337
Okayama Mount Ushiro 1,345
Shimane Mount Osorakan 1,346
Hiroshima Mount Osorakan 1,346
Shiga Mount Ibuki 1,377
Wakayama Mount Ryūjin 1,382
Aichi Mount Chausu 1,415
Nagasaki Mount Unzen 1,486
Hyogo Mount Hyōno 1,510
Aomori Mount Iwaki 1,625
Akita Mount Akita-Komagatake 1,637
Kanagawa Mount Hiru 1,673
Mie Mount Ōdaigahara 1,695
Tottori Mount Daisen 1,729
Kumamoto Mount Kunimi 1,739
Miyazaki Mount Sobo 1,756
Ōita Mount Kujū 1,791
Miyagi Mount Byōbu 1,825
Kochi Mount Miune 1,893
Nara Prefecture Mount Hakkyō 1,915
Kagoshima Mount Miyanoura 1,936
Tokushima Mount Tsurugi 1,955
Ehime Mount Ishizuchi 1,982
Tokyo Mount Kumotori 2,017
Iwate Mount Iwate 2,038
Fukui Mount Sannomine 2,095
Yamagata Mount Chōkai 2,236
Hokkaido Daisetsuzan 2,291
Fukushima Mount Hiuchigatake 2,356
Saitama Mount Sanpō 2,483
Tochigi Mount Nikkō-Shirane 2,578
Gunma Mount Nikkō-Shirane 2,578
Ishikawa Mount Haku 2,702
Niigata Mount Korenge 2,766
Toyama Mount Tate 3,015
Nagano Mount Hotakadake 3,190
Gifu Mount Hotakadake 3,190
Yamanashi Mount Fuji 3,776
Shizuoka Mount Fuji 3,776

Data from the Geospacial Information Authority of Japan.

The flattest prefecture? Yamanashi
Domo arigato

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