Railway development drives Tokyo’s growth as world’s largest metro area

Transportation

Outward expansion brings influx from rural regions as Japan’s total population declines

People head for Tsukuba Station on the TX line during morning rush hour on Oct.1 in Tsukuba, Ibaraki prefecture. (Photo by Daishi Abe)

DAISHI ABE

October 13, 2025 17:01 JST

TOKYO — The continuing development of Tokyo’s railway infrastructure is fueling further growth of the capital’s sprawling metropolitan area, solidifying its status as the world’s largest with 37 million people — about a third of Japan’s total population.