**Is Japan or Russia happy about their relative lack of children? Or are they quite worried?**
The same question for China?
China is having a weird problem due to too many male births compared to female. Instead of 1:1 it something like 116:100. In the hinterlands, there are starting to be kidnappings of women from nearby countries for brides. That’s where their one child policy got them. If a couple had a boy first, they stopped. if they had a girl first, a certain number of them would go on and try for a boy.
And China is also having another problem they never had before— people who won’t care for their elderly parents.
Finally, they are uncertain as to what China will be like when no one has siblings or cousins. Each family tree has no branches. How does that affect society? They are not sure.