Tokyo (東京, Tōkyō) is Japan's capital and the world's most populous metropolis. It is also one of Japan's 47 prefectures, consisting of 23 central city wards and multiple cities, towns and villages west of the city centre. The lzu and Ogasawara Islands are also part of Tokyo.
Osaka (大阪, Osaka) is Japan's second largest metropolitan area after Tokyo. It has been the economic powerhouse of the Kansai Region for many centuries. Osaka was formerly known as Naniwa. Before the Nara Period, when the capital used to be moved with the reign of each new emperor, Naniwa was once Japan's capital city, the first one ever known.