USDJPY has a number of trends going against it to force price action downwards. Technicals and fundamentals are not on the dollar's side against the yen. Traders can see a number of oscillators and MAs suggesting USDJPY is overbought and due for a reversal. Moreover and probably more impactful are the fundamentals of the global economy which suggest major growth centers (Europe and China) are slowing down. US treasury yields suggest we are heading towards a recession and US GDP growth is probably going to be less than previous quarter for the second quarter in a row. Because of this, the yen will be heavily invested into which will partially be a result of institutional hedging, partially Japanese capital flows returning to Japan. While the dollar will also benefit from this, it will probably not benefit as much as the yen in the short term since the US economy is still strong and many in the US still want to be exposed to risk-on assets like equity markets.
In spite of this, sentiment indicators suggest the yen is set for a bullish move, but this can quickly reverse. You can find that data here dailyfx.com/sentiment?ref=SubNav and you can find more analysis of currencies and indexes here anthonylaurence.wordpress.com