[unscaled]

Rural areas and smaller cities.

And it's not really a matter of low birthrate at these places. In fact, Tokyo has consistently had the lowest birthrate of all Japanese prefectures over the last few decades. The problem is that young people are migrating to large metropolitan areas in search for better opportunities.

It's also worth noting that despite the image, Japan's birth rate is HIGH for its region and among developed countries it is the almost the highest. Japan's fertility is higher than China's, Hong Kong, Macao, Singapore, South Korea and Taiwan. The only arguably developed state in Asia which has a higher fertility rate is Brunei and I don't really know if it counts - it's very conservative and the economy is mostly based on oil and gas.

Japan's problem is that it has industrialized earlier than its Asian neighbors and the effects of low birth rates are already very evident (in the countryside). It also got the attention in western media as the poster child for low birth rate, but it shouldn't be — that honor should probably go to South Korea (fertility rate of 0.72 in 2023).