So I’m back in the United States, and friends and family ask me over coffee and drinks: how many people live in Tokyo? The answer requires explanation—some sources say 8 million, others say 12.5 million, others 34.5 million. It’s not that the Japanese census is that unreliable. Instead, distinctions must be carefully made between the 23 wards of Tokyo, Tokyo Metropolis/Prefecture, and the Greater Tokyo Area.
Tokyo is the de facto capital of Japan, but there’s nothing in law that defines this as such. Tokyo is also the only prefecture called a “metropolis,” but there is no legal difference between Tokyo and other prefectures. The prefecture is made up of villages and cities, the same as any other prefecture, except that in the east the municipalities are called ku, or “wards.”
These 23 wards are just ordinary municipalities that are functionally the same as a city, but exist under a different name as a holdover from the pre-war local government regime. There is no unifying body or collective unit that binds these 23 wards together apart from the rest of Tokyo prefecture, but these 23 wards are collectively considered to be the heart of urban Tokyo. The population of Tokyo prefecture is about 12.5 million; the 23 wards have a collective population of about 8.5 million.
The capital of Japan; the green dot in the center of the map is the Imperial Palace.
But as the above map shows, the borders don’t mean the city stops. In many ways, nearby cities Chiba, Kawasaki, and Yokohama share more in common with the 23 wards than the mountains in western Tokyo Prefecture. And the three neighboring prefectures of Saitama, Kanagawa, and Chiba are therefore often included in the definition of Greater Tokyo, or Shuto Ken.
Tokyo’s 12.5 million people, Kanagawa’s 9 million, Saitama’s 7 million, and Chiba’s 6 million make for a combined total of 34.5 million people in this greater block, which is about 25% of Japan’s entire population concentrated in one area.
The four prefectures of Greater Tokyo
So that’s the short answer to the question that makes up this post title.