After its devastation in World War II, Tokyo saw a rapid population inflow in the 1960s on the back of Japan's strong economic recovery, and some 14 million people now live in the Japanese capital.

Meanwhile, the Japanese government in fiscal 2015 started to work on a comprehensive strategy for local revitalization to help stem depopulation in regional areas and rev up their economies.

As the population concentration in Tokyo has accelerated since then, however, the government began to take a different approach in the current fiscal 2025 in anticipation of a population decline.

Experts stress the importance of setting up a system in which industrial resources are circulated locally in order to create a sustainable society.

World War II claimed the lives of about 3.1 million people, including civilians. Large cities were hit by heavy air raids by the Allied powers, and the population of Tokyo fell to 3.49 million in 1945, when the war ended, from 7.35 million in 1940.

After the postwar turmoil subsided, Japan entered a period of strong economic expansion, backed by the growth of steelmakers, machinery makers and other heavy industries.

Industrial cities that were scattered around the country gradually declined, while functions to control factories that mass-produce automobiles, household appliances and other products were concentrated in urban cities.

According to internal affairs ministry data based on the basic resident register, the Tokyo metropolitan area logged a record net population inflow of 388,000 in 1962. Other areas recorded a net population decrease of 651,000 in 1961.

As urban overcrowding became a problem, the second cabinet of then Prime Minister Hayato Ikeda drew up a plan in 1962 to promote the relocation of factories to regional areas.

Economic turmoil caused by the oil crises in the 1970s and the collapse of the speculation-driven bubble economy in the early 1990s temporarily curbed population inflows into urban areas.

Naohiko Jinno, honorary professor at the University of Tokyo, said: "The oil crises were a warning that the era of the heavy industries was over. However, Japan did not change its industrial structure, with companies moving their factories overseas in search of cheap labor and control functions being concentrated in Tokyo as a result."

In fiscal 2015, the cabinet of then-Prime Minister Shinzo Abe launched a regional revitalization program featuring measures to promote migrations to regional areas in an effort to halt the concentration in Tokyo and a drop in Japan's population.

But the situation is serious.

According to the internal affairs ministry, Japan's population stood at 120.65 million as of January this year, down by 900,000 from a year before. Of Japan's 47 prefectures, only Tokyo continues to enjoy population growth.

A senior Cabinet Secretariat official said, "We may not have faced up to the scenario that the country's population would decrease so rapidly."

Learning lessons from this, the government of Prime Minister Shigeru Ishiba adopted in June this year a basic concept for the Regional Revitalization 2.0 initiative.

Measures in the initiative will be implemented over the next 10 years to make sure that local communities continue to exist even if the population continues to decline.

Through the initiative, the government aims to double the proportion of young people moving out of the Tokyo area to rural areas and increase the connected population, or nonresidents who steadily interact with regional areas, to a total of 100 million.

Jinno said, "People who know well about their own communities must think about how to develop the areas," rather than attracting factories that have nothing to do with the regions.

"The risk of war will become very high if confrontations between countries increase and military buildups create a very tense situation," Jinno said, expressing concern over countries' possible tilting to the right.

"Life will be threatened by global events unless each region creates a society in which life and industries circulate," he warned.