Japan’s population dropped by approximately 3.1 million people, or 2.5%, between 2020 and 2025, falling to about 123.05 million according to preliminary census data released October 1, 2025 [1, 2, 3, 4, 5, 6, 7, 8, 9].

This is the largest population decline recorded since Japan began census surveys in 1920. The recent drop is more than triple the previous decline from 2015 to 2020 when the population first shrank since census records began [10, 11, 12, 1, 3, 4, 5, 6, 8, 9]. Government spokesman Minoru Kihara said, "The data once again confirmed the population decline in our nation is deepening" [10].

The decline affected almost all regions. Only Tokyo and Okinawa prefectures saw population rises, of 1.4% and 0.1% respectively. The other 45 prefectures reported decreases, with Hokkaido losing the most residents—about 239,000 fewer people [1, 2, 3, 4, 5, 6, 7, 8, 9]. The combined population of the Tokyo metropolitan area, including Kanagawa, Saitama and Chiba, reached roughly 37.0 million, surpassing 30.1% of the national total for the first time [1, 2, 5].

Urban areas also felt the decline. Prefectures such as Saitama, Chiba, Kanagawa and Aichi, which had previously seen growth, now showed population losses. Osaka’s population fell by 0.8%, dropping below 8.8 million for the first time in three decades [3, 4, 5, 7, 8].

The population decrease results mainly from low birth rates and an aging population, leading to a natural decrease where deaths outnumber births. Births in 2025 totaled 705,809, marking the 10th consecutive year of decline. The average household size dropped to 2.15 persons, the smallest since records began in 1970, even as the number of households rose by 2.3% to a record 57.12 million [10, 11, 12, 1, 2, 3, 4, 5, 6, 9].

Prime Minister Sanae Takaichi is promoting stricter immigration policies despite the population shrinkage, reflecting ongoing political debate about the country’s demographic challenges [10, 11, 12, 1].

The census data confirm the continuation of a trend that began with the 2015 decline, marking three consecutive population drops [10, 11, 12, 4, 9]. Japan’s next major demographic update will come with mid-decade estimates and policy reviews scheduled in the coming year.