Would this have something to do with improving natality rates?
I am not entirely sure if this will help though. Birth Rate in Japan, ( or in any nation ) is a complex issues. Both cultural and economics. Why would anyone want a baby when they can barely afford themselves decent standard of living? ( Standard being different from person to person )
Rent and food even in Tokyo is much cheaper than even medium sized cities in the states.
People might not be able to afford a luxurious lifestyle in Japan, and economists standard of living models may tell you otherwise, but the standard of living for a typical person in Japan is high
Once it becomes a norm, people want more.
There are macro and microeconomic reasons , but not being able to afford to raise a child is not one of them. Most of the reasons are social.