Drilling to the 5 minute chart below, the price in the Asian session took a dip that saw the price move below the 100/200 bar MA (blue and green lines), but only by a few pips before rotating back higher and resuming the trend move higher.
The consolidation near the highs over the last few hours, has allowed the 100 bar MA (blue line) to catch up to the price, but so far the moving average is holding support.
A move below it does not ruin the bullish momentum, but does give sellers against the resistance above small comfort that the trade plan is progressing.
Getting below the 38.2% retracement of the range today at 121.44 and the 50% at 121.348 would hurt the trend move bias more, and give sellers more comfort. The rising 200 bar moving averages (green line in the chart below) also near the 50% midpoint currently (green line) increasing that areas importance.
For a further background review of the trend move higher in the USDJPY, see post HERE.