Japan's population decline is now affecting not only rural areas but also major metropolitan regions. Yokohama, the largest city in Kanagawa Prefecture, has recorded its first population decrease since World War II, with Kanagawa, Chiba, and Saitama also experiencing declines. Last year, the total fertility rate fell to a historic low of 1.14. Even the metropolitan areas, which had absorbed population outflows from rural regions, can no longer compensate for the decline in births and the natural decrease due to aging.
According to preliminary data from the Ministry of Internal Affairs and Communications based on the 2025 national census, Japan's total population was 123,049,524 as of October 1 last year, a decrease of 3,096,575 (2.5%) from five years earlier, marking the largest decline on record. The only areas that saw population growth were Tokyo and Okinawa. The Asahi Shimbun reported that 45 of Japan's 47 prefectures experienced population declines, indicating that this trend has become structural and is accelerating.
Notably, changes in the metropolitan area are striking. The Yomiuri Shimbun pointed out that “the wave of population decline has reached the Tokyo area.” Despite maintaining a net increase in population due to more people moving in than out, the natural decrease in Kanagawa, Chiba, and Saitama has led to an overall population drop. Tokyo's population increased to 14,246,219, but the growth rate has significantly slowed from 532,000 five years ago to just 199,000.
A symbolic case is Yokohama. According to the Nihon Keizai Shimbun (Nikkei), Yokohama's population is now 3,754,840, a decrease of 22,651 from five years ago, marking the first decline since the post-war period. The number of deaths (80,858) exceeded the number of births, despite a net migration gain of 74,320. Yokohama, which has grown as a residential city for Tokyo, is also facing aging issues. Among the 20 designated cities, 13, including Hiroshima, Kyoto, and Kobe, have also seen population declines.
The speed of population decline is confirmed by demographic statistics. The Ministry of Health, Labour and Welfare reported on June 3 that the total fertility rate has dropped for ten consecutive years to 1.14, setting a new record low. The number of births in Japan was 671,236, the lowest since records began. The National Institute of Population and Social Security Research had projected a fertility rate of 1.25 for 2023, but the actual figure is closer to the pessimistic low estimate of 1.10. The point at which the number of births falls below 680,000 is now expected to occur in 2040, but this milestone has arrived 15 years earlier than anticipated.
Even within the concentration of population in Tokyo, trends are mixed. While the overall population of the 23 wards has increased, the three wards of Chiyoda, Shibuya, and Meguro, which have high living costs, have seen declines. The Nikkei suggested that rising housing costs may have pushed families with children out of the city center. Conversely, the central area where the Harumi Flag residential complex was built for the Tokyo Olympics has seen a 7.53% increase, the highest in years.
The population decline is also impacting public utility costs. According to the Yomiuri Shimbun, Yokosuka City in Kanagawa Prefecture, which experienced the 11th largest population decline (23,100), plans to raise water and sewage fees starting in October due to decreased revenue. Even with fewer users, maintaining facilities remains costly.
The burden of social security is also increasing. Takuya Hoshino, chief economist at Dai-ichi Life Research Institute, estimates that the social security costs borne by each working individual will rise by about 20%, from 2.07 million yen in 2025 to 2.48 million yen in 2050. Even with more women and elderly people in the workforce, there are limits to preventing the decline in the working-age population.
Hiroya Masuda, a senior advisor at Nomura Research Institute, told the Nikkei, “Japan has entered a period where the population will decline by one million each year,” predicting that the total population will fall to the 110 million range by the 2030 national census. He emphasized that merely encouraging childbirth or attracting businesses will not suffice; Japan must restructure its administration, urban planning, infrastructure, and social security systems to adapt to the shrinking population.
* This article has been translated by AI.
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