Japan is a stratovolcanic archipelago of 6,852 islands. The four largest are Honshu, Hokkaido, Kyushu, and Shikoku, which make up about ninety-seven percent of Japan's land area. Japan's population of 126 million is the world's tenth largest. Approximately 9.1 million people live in Tokyo, the capital city of Japan, which is the second largest city proper in the OECD. The Greater Tokyo Area, which includes Tokyo and several surrounding prefectures, is the world's largest metropolitan area with over 35 million residents and the world's largest urban agglomeration economy.