Depending on how commited Japan is, I think you can threaten the the US pretty good.
Example  (Assume US goes with an Atlantic Focus).
As Japan in rds 1-2, buy trns and inf (kind of a normal play). Â You can even get away with a rd 1 IC (on Man).
Set your Japan to Asia Shuck-Schuck via sz 60 to Bury.
Once the US BB hits the Eus sz, then as Japan you are really safe.
Say J3 you unload 8 inf to bury (bought 8 and place on Japan).
Now on J4 you dump 8 inf to Wcan (from Japan) and move the 8 inf from Bury to Sfe.
With wise purchasing you can keep dumping 6-8 units into Canada and still place 3-5 in Aisa (at this point for defense only) to hold your lines at Sin and Yak.
Obviously you won’t be making a run at Moscow, but this can be handy if you deem it impossible to get to Moscow and take anyway.
The problem for the US is, if they didn’t start their inf train from Wus, Japan can squeeze in at Cus or Ecan (or both) and force the US to take them back.
IMO, you play J1-3 fairly conventionally, judge the status at that time and then decide whether you can make a play or not.
As long as you are Shucking from Sz 60 to Bury on J2-3, and placing 4-8 units on Japan, I think the opportunity is there to cause some trouble if the US get sloppy early on.
Edit:
Switch snuck in a post. But I agree.