Tokyo at night
Tokyo is one of the 47 prefectures of Japan, and among the prefectures it is unique in providing certain municipal services characteristic of city. 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 most populous city in the country. The twenty-three special wards of Tokyo, although each administratively a city in its own right, constitute the area informally considered as the "city of Tokyo" and are collectively one of the largest cities in the world. Tokyo has the largest metropolitan gross domestic product in the world for a city, and it held the title of the world's most expensive city for over a decade from 1992 through 2005.
Tokyo is considered one of the world's major global cities and a megacity. The name "Tokyo" refers variously to Tokyo Metropolis (the prefecture) as a whole, or only to the main urban mass under its jurisdiction or even the whole of Greater Tokyo Area, which includes Tokyo, Kanagawa, Saitama, Chiba, Gunma, Tochigi, Ibaraki, and Yamanashi prefectures.