First, you should never make comments on Japanese growth or lack thereof without taking demography into account. Japan has low fertility and low immigration; this has translated into a dramatically aging population and a declining working-age population.
Surprisingly:
I’ve used a log scale, so you can view vertical distances as percentage changes. If we look at growth from the early 1990s to the business cycle peak in 2007, we have growth of about 1.2% per year. That’s actually not bad; you can argue that demographically adjusted, the whole tale of Japanese stagnation is a myth.
What is true is that there were two long periods of depressed output relative to trend, one in the mid-1990s and another, much worse, between 1997 and 2007. And one other thing: Japanese monetary policy was still up against the zero lower bound in 2007, leaving it no room to counter the Great Recession, and hence leaving Japan open to a deep slump when exports plunged.
So how do we think about this problem? Here’s my take. Japan has pretty much spent the past 20 years in a liquidity trap; as I’ve been explaining for years, one way to understand such traps is that they happen when, even at a zero real interest rate, the amount that people would want to save at full employment exceeds the amount they would be willing to invest, also at full employment
But Japanese policy has never sought to achieve this. Deficit spending has put part, but only part, of the excess desired private saving to work; this has mitigated the slump, but not produced a booming economy, except perhaps briefly circa 2007. And the Bank of Japan has always pulled back on monetary policy when the economy looks better, instead of doing what it should, which is to keep the pedal to the metal until the inflation rate is solidly into positive territory.
The point is that as an analytical matter, Japan’s experience is perfectly consistent with an IS-LM type story, with nothing in there to suggest that fiscal stimulus has somehow backfired; stimulus has done exactly what you’d expect given its limited size and the refusal to take the opportunity to break out of the liquidity trap.