On top of how many? Still though, that's insane. But with such an aged population it's no wonder. Japan is in a vicious cycle and many other countries are getting there.
Yep. Japans declining birth rates and aging are working against it. They're trying to keep up with current output with a smaller population. China will be facing something much worse because it struggles to attract immigration to offset population decline and will likely follow the same steps - increase hours to maintain output.
Most of the developed world has this problem, in fact. The only places where it is less evident are those where they receive enough immigration from developing countries.
Once the "developing world" eventually joins the "developed world" and begins to suffer the same declining birth issue, we are going to have to rethink our model of economics to accommodate for a shrinking global population of workers. The good news is that AI and automation might solve that problem for us, but we will have to see who can actually integrate these solutions responsibly, without consolidating all of the financial resources towards wealthy oligarchs who own the technology.
Even here in Canada we may run to that problem shortly. The cost of living here has gotten so high. At least everyday items weren't bad when housing prices were but everything has gone up in the last year I've been seeing articles on immigrants moving back because of how expensive it is here. They got no money to send back let alone for themselves.