Whilst the rest of the Worlds post Global Financial Crisis recovery began in 2009, Japan's was delayed until the massive stimulus by Prime Minister Abe in 2011. This was offset by a JPYUSD fall in almost perfect sync. Interestingly the recent rally in 2017 has been positively correlated to JPYUSD , demonstrating that the rally is driven by higher and growth expectations, building a solid case for further gains.
In summary the case for a Japan bull market is:
1. Improving outlook with a strengthening domestic economy
2. Currently attractive equity valuations compared to developed market peers
3. picking up
4. Continued monetary stimulus