Tokyo officially Tokyo Metropolis, is the capital of Japan and one of its 47 prefectures. The Greater Tokyo Area is the most populous metropolitan area in the world. It is the seat of the Emperor of Japan and the Japanese government. Tokyo is in the Kantō region on the southeastern side of the main island Honshu and includes the Izu Islands and Ogasawara Islands. Formerly known as Edo, it has been the de facto seat of government since 1603 when ShogunTokugawa Ieyasu made the city his headquarters. It officially became the capital after Emperor Meiji moved his seat to the city from the old capital of Kyoto in 1868; at that time Edo was renamed Tokyo. Tokyo Metropolis was formed in 1943 from the merger of the former Tokyo and the city of Tokyo.

Tokyo is often referred to as a city, but is officially known and governed as a "metropolitan prefecture", which differs from and combines elements of a city and a prefecture, a characteristic unique to Tokyo. The Tokyo metropolitan government administers the 23 Special Wards of Tokyo, which cover the area that was the City of Tokyo before it merged and became the metropolitan prefecture in 1943. The metropolitan government also administers 39 municipalities in the western part of the prefecture and the two outlying island chains. The population of the special wards is over 9 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 37.8 million people and the world's largest urban agglomeration economy. The city hosts 51 of the Fortune Global 500 companies, the highest number of any city in the world. Tokyo ranked third in the International Financial Centres Development IndexEdit. The city is also home to various television networks such as Fuji TV, Tokyo MX, TV Tokyo, TV Asahi, Nippon Television, NHK and the Tokyo Broadcasting System.

Tokyo ranked first in the Global Economic Power Index and fourth in the Global Cities Index. The city is considered an alpha+ world city – as listed by the GaWC’s 2008 inventory – and in 2014, Tokyo was ranked first in the "Best overall experience" category of TripAdvisor's World City Survey (the city also ranked first in the following categories: "helpfulness of locals", "nightlife", "shopping", "local public transportation" and "cleanliness of streets"). In 2015, Tokyo was ranked as the 11th most expensive city for expatriates, according to the Mercer consulting firm, and also the world's 11th most expensive city, according to the Economist Intelligence Unit's cost-of-living survey. In 2015, Tokyo was named the Most Liveable City in the world by the magazine Monocle. The Michelin Guide has awarded Tokyo by far the most Michelin stars of any city in the world. Tokyo was ranked first out of all fifty cities in the 2015 Safe Cities Index. The 2016 edition of QS Best Student Cities ranked Tokyo as the 3rd-best city in the world to be a university student. Tokyo hosted the 1964 Summer Olympics, the 1979 G-7 summit, the 1986 G-7 summit, and the 1993 G-7 summit, and will host the 2020 Summer Olympics and the 2020 Summer Paralympics.