Tokyo , officially the Tokyo Metropolis (東京都, Tōkyō-to), is the capital and the most populous prefecture of Japan. Tokyo's metropolitan area (including neighboring prefectures as well as Tochigi, Gunma and Ibaraki; 13,452 square kilometers or 5,194 square miles) is the most populous in the world, with an estimated 37.468 million residents as of 2018; although this number has been gradually decreasing since then, the prefecture itself has a population of 14.09 million people while the prefecture's central 23 special wards have a population of 9.73 million. Located at the head of Tokyo Bay, the prefecture forms part of the Kantō region on the central coast of Honshu, Japan's largest island. Tokyo serves as Japan's economic center and is the seat of both the Japanese government and the Emperor of Japan.