Claim: Tokyo was known formerly as Edo.

Tokyo -LRB- -LSB- toːkjoː -RSB- , -LSB- langˈtoʊki.oʊ -RSB- -RRB- , 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 Shogun Tokugawa 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 and the .   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 -LRB- each governed as an individual city -RRB- , 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 -LRB- the city also ranked first in the following categories : `` helpfulness of locals '' , `` nightlife '' , `` shopping '' , `` local public transportation '' and `` cleanliness of streets '' -RRB- . 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 ranked first in the world in the 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 .