I was browsing the web earlier, when I happened to come across a blog post about Japan written by Paul Krugman in February of 2013. In the post, Krugman acknowledges the important role that demography has played in Japan's apparent stagnation:
When people try to assess how Japan has done since its late-80s bubble burst, they often look at per capita GDP. But this can be deeply misleading, because of Japan's low birth rate and ageing population.
He proceeds to show that Japanese GDP per working-age person has actually been improving relative to the US since the late 1990s. As I have argued before, this is not to say that that Japan has performed spectacularly over recent years. But to quote Krugman again, "the seemingly overwhelming failure you see if you don't take demography into account just isn't clear."