You can't, really. Tickets are sold in currency of the origination point, so the one-way origination point of your return will make it return prices in Yen. The translation to dollars happens during the payment transaction (your CC will be charged in Yen and your bank will convert it dollars). A third party site may offer it in dollars for you but that would an be an already-converted figure and the FX may not be very favorable, so check before you buy.