Tokyo, officially the Tokyo Metropolis, is the capital and most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is one of the most populous urban areas in the world. The Greater Tokyo Area, which includes Tokyo and parts of six neighboring prefectures, is the most populous metropolitan area in the world, with 41 million residents as of 2024.

Lying at the head of Tokyo Bay, Tokyo is part of the Kantō region, on the central coast of Honshu, Japan's largest island. It is Japan's economic center and the seat of the Japanese government and the Emperor of Japan. The Tokyo Metropolitan Government administers Tokyo's central 23 special wards, which formerly made up Tokyo City; various commuter towns and suburbs in its western area; and two outlying island chains, the Tokyo Islands. Although most of the world recognizes Tokyo as a city, since 1943 its governing structure has been more akin to that of a prefecture, with an accompanying Governor and Assembly taking precedence over the smaller municipal governments that make up the metropolis. Special wards in Tokyo include Chiyoda, the site of the National Diet Building and the Tokyo Imperial Palace; Shinjuku, the city's administrative center; and Shibuya, a hub of commerce and business.

Before the 17th century, Tokyo, then known as Edo, was mainly a fishing village. It gained political prominence in 1603 when it became the seat of the Tokugawa shogunate.