Quantitative easing, Yen depreciation... What they need to do is figure out a way to grow the population locally or through large-scale immigration. I'm afraid this is the fate that awaits the developed world (or countries with low population growth). Japan is like a canary in the mine of post-industrialism. It'll be interesting to see what they figure out for their society and the lessons they might have for us.
They have 5% unemployment, and, after a quick check, it seems like a similar labour force to population ratio to the UK and US. I'm not an economist, but in their position, what would mass immigration solve?
No discussion of Japan's economy (whether it's government debt, inflation rates, recession, etc.) is complete without mentioning that the unemployment rate is 3.6%, the 2nd-lowest (behind South Korea) in the OECD.[0]
So all the doom-and-gloom about Japan's future prospects and what they're doing and should be doing has to be balanced by the continued commitment by the successive Japanese governments to maintaining full employment.