Correlation between 10y UST yields and USD/JPY performance is nearly 1:1, which may mean that movement in this pair is not due to Yen strength, but rather capital rotating from other US investments into US treasuries. It is likely that this means that investment capital is neither leaving nor entering the US. In such a scenario, Yen strength vs the dollar is driven by US manufacturer purchasing, and other trade-related exchange, in the near term. Yen weakness should be showing up in other currencies, but the only evidence of this is the subdued performance of the AUD/JPY and NZD/JPY. Further evidence may come from private equity reports from Preqin - capital raising for US funds should slow in Q1.
All this adds up to speculator uncertainty in the coming weeks while international trade data (and of course the all-important jobs data) is released. The direction for the intermediate and long term for this pair is still up, and we are targeting 124 by the end of Q2.