Tokyo is Japan's capital and the country's largest city. Tokyo is also one of Japan's 47 prefectures, but is called a metropolis (to) rather than a prefecture (ken). The metropolis of Tokyo consists of 23 city wards (ku), 26 cities, 5 towns and 8 villages, including the Izu and Ogasawara Islands, several small Pacific Islands in the south of Japan's main island Honshu.

The 23 city wards (ku) are the center of Tokyo and make up about one third of the metropolis' area, while housing roughly eight of Tokyo's approximately twelve million residents.

Prior to 1868, Tokyo was known as Edo. A small castle town in the 16th century, Edo became Japan's political center in 1603 when Tokugawa Ieyasu established his feudal government there. A few decades later, Edo had grown into one of the world's most populous cities.

With the Meiji Restoration of 1868, the emperor and capital where moved from Kyoto to Edo, which was renamed Tokyo ("Eastern Capital"). Large parts of Tokyo were destroyed in the Great Kanto Earthquake of 1923 and in the air raids of 1945.