I'm not certain about this Monday specifically but as a rule FX trades regardless of most if not all US holidays.
Right, I think we'll see a slowing type impact for probably a 6-hour period, but, remember too that in thin volume moves can be exaggerated. Profitable trades should still abound especially with USD/JPY longs.
Check with your broker. They should have let you know their Monday hours by now. Forex.com's desk opens at 1600 EST Monday, I think. That's about 75 minutes from now. And I'm smelling what Skalpz is cooking ... though by way of the EURUSD rather than USDJPY ...