Abortion is technically illegal in Japan but with exceptions so broad it is widely practiced and accepted today. So start with banning abortions in practice.
Losing medical license for doctors all the way up to death penalty.
Re-impregnating women in the lab who have had abortions.Make getting an abortion pointless.
Banning birth control. Better to have children unwanted by their mother than no children at all.
Using the tax code to punitively tax the childless. You can’t lead a luxurious lifestyle INSTEAD of having and spending money on children.
Promotions at work only for those with 2 children or more. In other words, promotions only for patriots.
Reversing the Japanese fertility rate will require policies that will make Western governments go apeS%!t.
There are only two options for Japanese policymakers to reverse dramatic population declines: increase the birthrate or dramatically increase immigrations. 97%+ of Japanese are adamantly against large scale immigration.
They have largely run out of carrots to increase the birthrate. Free healthcare for kids,free childcare, child tax credits and ~$5k grant for baby supplies. The only unused tools in the arsenal are sticks.
Nothing is guaranteed to success. A wholesale societal revolt could happen. A society hellbent on committing suicide can’t be stopped.
Of course they could always dump the burden of the elderly by making death of elderly patriotic