Japanese growth is still sluggish. Consumers aren’t consuming much, and businesses aren’t investing. The government doesn't have many options to remedy this, and the Bank of Japan, which has sent both long-term and short-term interest rates into negative territory, has basically no more room to maneuver.
The dreaded Zero Lower Bound is starting to bite. The BOJ is buying more stocks, but this too has its limits -- eventually companies become de facto nationalized, as the government becomes the majority shareholder. That’s scary both because it would affect corporate governance, and because it would be politically unpopular. It’s also unclear how much of an economic boost the stock-purchasing program has given the country anyway. The BOJ could resort to policies like a higher inflation target or the much-discussed “helicopter money” approach, but so far it has been afraid to take these steps.