Japan's population declined by a record 2.5 per cent in a span of five years, according to census data released on Friday.The steep decline has yet again highlighted the demographic challenges faced by Japan’s rapidly ageing society, despite the government implementing a series of measures to address the crisis.Japan's census, released every five years, found that the country's population slipped to 123 million in 2025, more than three million fewer than the previous data release in 2020.It is the third straight survey in which the country’s total population has declined.The new data showed the biggest population decrease since the survey began in 1920, with the government attributing the drop to the country's greying demography and widening natural decrease – when a country’s deaths outstrip births.The World Bank has previously ranked Japan as having the world’s second-oldest population, surpassed only by Monaco. Japan also has one of the world's lowest birth rates and recorded its lowest child population in 2025 since the country began such record-keeping in the 1950s. Data released earlier in May found children accounted for 10.8 per cent of the total population, the lowest proportion on record."It was confirmed again that the population decline is advancing even further," chief cabinet secretary Minoru Kihara told reporters. He pledged to "comprehensively promote various measures" in an effort to address the challenges of a falling population.Mr Kihara stressed the need to promote decentralisation of people and businesses to regional areas to "correct the overconcentration in Tokyo", according to Kyodo News.The census revealed that the population in Tokyo grew by 1.4 per cent and Okinawa witnessed a 0.1 per cent rise, while the rest of the 45 prefectures saw declines.The census found that the number of foreign residents climbed to about 3.21 million, surpassing the previous high of roughly 2.75 million recorded in 2020. Although immigration has been touted as a possible solution to Japan's declining population, last year the country voted in a leader in Sanae Takaichi who has vowed a tougher stance on letting foreigners enter the country.The government has identified the period through 2030 as a “final opportunity to reverse the trend”, even though steps such as expanding financial support for child-rearing households have not helped thus far.