Did you know that in the Metropolitan area of Tokyo live nearly as many people as live in Spain? The large area of Tokyo (Tōkyō-ken), also known as the Tokyo-Yokohama area is the largest metropolitan area of Japan, and also the largest in the world. According to studies, Tokyo-ken is consisted of the prefectures of Tokyo, Kanagawa, Chiba and Saitama, concentrating around 38 million people.
Some other countries with a similar population like the metropolitan area of Tokyo-Yokohama:
Colombia — 45 million
Argentina — 38 million