Japan is facing a population crisis—so Tokyo, its largest city, will try to solve the problem with something new: a four-day workweek.

Starting in April this year, the Tokyo Metropolitan government, one of the country’s largest employers, started to allow its employees to work only four days a week. It is also adding a new “childcare partial leave” policy, which will allow some employees to work two fewer hours per day. The goal is to help employees who are parents balance childcare and work, said Tokyo Governor Yuriko Koike.

“We will continue to review work styles flexibly to ensure that women do not have to sacrifice their careers due to life events such as childbirth or child-rearing,” Koike said in a speech during the Tokyo Metropolitan Assembly’s regular session in December 2024, the Japan Times reported.

The new policies come as the birth rate in Japan hit a record low for the first half of the year. From January to June, the country recorded 339,280 births, around 10,000 fewer births than during the same period last year, according to the Ministry of Health, Labor, and Welfare.

Japan isn’t the only country facing declining fertility. According to the New Yorker, by 2100, 97% of the world’s countries are predicted to be below replacement, or the number of births required to maintain a stable population. South Korea has the lowest fertility rate in the world, and dog strollers outsold baby strollers there in 2023. While the United Nations predicts the global population will continue to grow long into this century, some pro-natalists (including, notably, the world’s richest man and father of 13 Elon Musk) worry declining birth rates are the world’s biggest looming problem.

Japan’s total fertility rate, which represents the number of children a woman has in her lifetime, stood at 1.2 in 2023, and in Tokyo, the birth rate was even lower at 0.99. To maintain a broadly stable population, a birth rate of 2.1 is required, according to the Organisation for Economic Co-operation and Development (OECD). The median age of a Japanese citizen is 49.9, according to the Central Intelligence Agency. In the U.S., the median age is 38.9.

Japan has taken drastic steps toward reversing its low birth rate. Starting in the 1990s, the government required companies to offer generous parental leave, added subsidies for day care, and started offering cash payments to parents. Earlier this year, the Tokyo government also launched its own dating app to help single people find a partner and marry.

Yet the birth rate has still fallen consistently over the past eight years, according to government data.

Moving to a four-day workweek could help address some of the core issues associated with Japan’s heavy work culture, which can especially weigh on working women. The gap between men and women when it comes to housework is one of the largest among OECD countries, with women in Japan engaging in five times more unpaid work, such as childcare and elder care, than men, according to the International Monetary Fund.

More than half of women who had fewer children than they would have preferred said they had fewer children because of the increased housework that another child would bring, according to the IMF.

In some cases, moving to a four-day workweek has been shown to improve housework equity. Men reported spending 22% more time on childcare and 23% more time on housework during a four-day workweek trial conducted across six countries by 4 Day Week Global, which advocates for the issue.

It would take a major societal change for the four-day workweek to catch on more broadly, but years of experiments have shown that working one day less a week improves employee productivity and well-being, said Peter Miscovich, the global future of work leader at real estate services company JLL.

“The upside from all of that has been less stress, less burnout, better rest, better sleep, less cost to the employee, higher levels of focus and concentration during the working hours, and in some cases, greater commitment to the organization as a result,” Miscovich told Fortune.

While four-day workweek tests like the one in Tokyo can be innovative experiments, they may not be the solution that some make them out to be, said Julia Hobsbawm, the founder of workplace consultancy Workathon and author of the book Working Assumptions: What We Thought We Knew About Work Before Covid and Generative AI—And What We Know Now.

“I firmly believe that there is no one-size-fits-all,” Hobsbawm told Fortune.

“In a time of increasing flexibility across working practices, both technological and human, you simply can’t say that the one size that might fit one industry, in one country, for one purpose, of a four-day week fits all.”