Tokyo (Japanese: 東京), is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of the world. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family. Tokyo is in the Kantō region on the southeastern side of the main island Honshu and includes the Izu Islands and Ogasawara Islands. Tokyo Metropolis was formed in 1943 from the merger of the former Tokyo Prefecture (東京府) and the city of Tokyo (東京市).

The Tokyo Metropolitan government administers the 23 special wards of Tokyo (each governed as a city), which cover the area that was the city of Tokyo, as well as 39 municipalities in the western part of the prefecture and the two outlying island chains. The population of the special wards is over 8 million people, with the total population of the prefecture exceeding 13 million. The prefecture is part of the world's most populous metropolitan area with upwards of 35 million people and the world's largest urban agglomeration economy with a GDP of US$1.479 trillion at purchasing power parity in 2008, ahead of New York City metropolitan area, which ranks second on the list. The city hosts 47 of the Fortune Global 500 companies, the highest amount of any city.

Tokyo has been described as one of the three "command centers" for the world economy, along with New York City and London. This city is considered an alpha+ world city, listed by the GaWC's 2008 inventory and ranked fourth among global cities by A.T. Kearney's 2012 Global Cities Index. In 2010 Tokyo was named the second most expensive city for expatriate employees, according to the Mercer and Economist Intelligence Unit cost-of-living surveys, and in 2009 named the third Most Liveable City and the World’s Most Livable Megalopolis by the magazine Monocle. The Michelin Guide has awarded Tokyo by far the most Michelin stars of any city in the world. Tokyo hosted the 1964 Summer Olympics and is currently bidding to host the 2020 Summer Olympics.