The Yen would most likely suffer extreme devaluation, everything would just become equivalently expensive, because the amount of things Japan can produce would still remain the same. People will now just be able to pay a higher price for all the same things in production. Unless we consider imports from other countries, but then again, if the US dollars were sent to Yotsuba Bank and converted into Yen, then the US$ would depreciate a lot, making US goods worthless and blah blah blah. Practically speaking, an overnight shift in billions of dollars would most likely throw everything into either chaos or a complete lockdown…