USDJPY seems to have found a bottom but must break above the bearish trend to well and truly confirm a bullish move. With Fed minutes coming up and the Dow/Nikkei 225 looking stable, we may indeed see some rational and calculable moves from this pair in the coming days.
I think the mover for usdjpy atm is news as there are a lot of news coming out from BOJ in the near future, the majority believe the news will be negative, and also a lot of people working in the bank think it would be good for them to have a weaker Yen. that's why you see an uptrend most likely at least on the long term