Japan's child population has declined for the 38th year in a row and is now at a record low, the government said.
The number of children younger than 15 stood at 15.22 million on April 1, down 180,000, or 1.2%, from last year, the Statistics Bureau said.
It is the lowest number since comparable data became available in 1950.
The figures were released ahead of Children's Day on May 5.
Japan's birthrate has remained low amid a lack of support for working women, who continue to face the burden of homemaking and other traditional roles, as well as excessively long working hours and high education costs.
With children making up just 12.1% of its population, Japan ranks lowest among countries with a population exceeding 40 million, followed by South Korea at 12.9% and Italy and Germany at 13.4%, according to the Statistics Bureau figures.
As of 2017, Japanese women on average gave birth to 1.43 children during their lifetimes. That compares with nearly 1.8 in the US and Britain.
According to the latest government statistics, the number of births in 2018 fell to 921,000, the lowest since Japan began recording such statistics in 1899.
Japan's total population fell by 448,000 people, a record decline, to 126 million.
The population is forecast to fall below 100 million by 2050, barring a huge influx of immigrants.
Japan last month started allowing more foreign workers to ease a labour crunch.
Prime minister Shinzo Abe has said ageing and the low birth rate are a national crisis. He has promised labour and other reforms to help alleviate the burden on families that discourage couples from having more children.
Longer life spans in Japan have added to rising costs for elderly care and social security.
Conservative legislators in Mr Abe's government have at times blamed the elderly or childless for long-term demographic trends.
Gaffe-prone finance minister Taro Aso earlier this year had to apologise for saying childless people are to blame for Japan's rising social security costs and declining population.