Sure, you could come out ahead if the rate falls significantly between when you exchange and when you go, less anything you could lock up in advance before your trip.

It's very easy to do the math once you know your spending and withdrawal patterns.

Not being a Wise user, it seems: deposit fees are ~$4 + 0.55%, withdrawal fees are 70yen + 1.75% after the first 30k yen/2 withdrawals, the ATM fees are iirc 2.2% (220 yen per 10k yen withdrawn).

So all the percentage-based fees add up to 4.5% if you use Wise for ATM withdrawals. At which point you're better off using the money exchange at 142 when the spot rate is 147 (142/147-1 is 3.5%).

You avoid the fees if using the debit card to pay for stuff, however Don't forget you also lose out on credit card points this way which is another couple percentage points.

And as mentioned you can partially lock in good rates by prepaying refundable hotel reservations, buying train tickets / passes in advance, and storing some up via mobile Suica.

Sources:
https://wise.com/us/pricing/receive
https://wise.com/help/articles/29357...-withdraw-cash