Tokyo, officially the Tokyo Metropolis, is the capital of Japan and one of the most populous cities in the world with a population of over 14 milli…Tokyo, officially the Tokyo Metropolis, is the capital of Japan and one of the most populous cities in the world with a population of over 14 million residents as of 2023. The Tokyo metropolitan area, which includes Tokyo and nearby prefectures, is the world's most-populous metropolitan area, with 40.8 million residents as of 2023, and is the second-largest metropolitan economy in the world after New York, with a 2022 gross metropolitan product estimated at US$2.08 trillion.