The Japanese economy has been growing painfully slowly since the asset price bubble burst in 1992. Initially, it was just a standard downturn following a stock market decline. The Japanese government, however, continued on a stop-go course of fiscal policy throughout the 1990s, and let bad debts mount in the financial system due to poor supervision. The economy has not recovered since. In fact, things have gotten worse with people saving more, but pulling their savings out of the Japanese private banking system, which contracts credit and then the economy further.
Fiscal policy works when it is tried.
The problem is that the Japanese government and the Ministry of Finance have way overstated the amount of fiscal stimulus in which they actually engaged. Japan did add the most to its debt in the 1990s, and has the most rapidly aging society, amongst the OECD economies. The relevance of these facts to the appropriate policy response at present, however, is questionable. There is no reason that this trend should not be reversible when growth returns. While the society is indeed aging, the demographic trends are so large that they can only be responded to with appropriate large measures - increasing the retirement age, the participation rate of women in the work force, or the rate of social security contribution.