My video discussions regularly remark how a strong dollar versus the yen is bearish for equities while a weak dollar index is also bearish for equities. The chart below is an attempt at displaying a "weathervane" for these FX background influences. The weathervane is most bullish when the dollar is weak and the yen is weaker, and most bearish when the dollar is strong and the yen is stronger.
click chart to enlarge
click chart to enlarge