Tokyo, officially Tokyo Metropolis, is one of the 47 prefectures of Japan. Located on the eastern side of the main island Honshū, Tokyo is unique among the prefectures, providing certain municipal services characteristic of a city, as defined by Japanese law.
Because it is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family, Tokyo is the de facto capital of Japan. The name Tokyo literally means eastern capital.
The twenty-three special wards of Tokyo, although each administratively a city in its own right, constitute the area often incorrectly considered to be the "city" of Tokyo and, if they were a city, would collectively be one of the largest cities in the world with a total population of over 8 million people. The total population of the prefecture exceeds 12 million.
The Greater Tokyo Area, centered on Tokyo but also including Chiba, Kanagawa, and Saitama, is the most populous metropolitan area in the world with a population of over 35 million people. It has been the world's most populous urban area since between 1965 and 1970, and despite Japan's overall declining population, is still growing.