Forex is a completely different game from miles&points, so I leave it to experts there, but when I look at 1mo back, USD/JPY hasn't moved more than 2%, which to me just business as usual. Election results made very little impact to my surprise.

I have a good chunk of assets in JPY, it was really strong against CAD back in Apr., but I was greedy and lost the opportunity to change them to CAD. However, I know it's cyclical, so I'll hold it for a while lol. Same goes with gold, I seem to always miss opportunities to sell.

I agree with other posters, I'd also say airfare is a lot more volatile than USD/JPY, I'd say grab it if you think it's a good price, regardless of forex forecast.

It's nice it shows forex fee separately in statements in USA as one poster mentioned. In Canada, it's usually around 2.5% stated in T&C, but on statements, they're never separate, you need to use a calculator, then they usually come +-2.5%. I have amazon.ca Visa which offers no forex fee, but I still get dinged up to 0.5%, because they use Visa's exchange rate, which is always slightly higher than what we see on xe.com.

FYI, ex-Canada tkts are priced and charged in CAD on delta.com, but when I redeemed a o/w reward tkt from Mexico to Canada, delta.com was showing fees in USD, not in MXN and I was charged accordingly.