And this is where year-end thin liquidity trading can be a factor in trading
Snap your fingers, and suddenly things change. From 113.15, USD/JPY just popped all the way to session highs of 113.38. But it's not just limited to USD/JPY, the yen is falling against all other major currencies as well.
Do take note that there is a large option expiry today for USD/JPY at 113.00 and also a large one tomorrow (as Eamonn pointed out here) at 113.50. That should keep the price contained between these two levels for the time being.
But also, the sudden spike coincides with GBP/JPY's high over the last week at 152.01. That's keeping a lid on the JPY weakness so far.
