NY is a japnese company. They only work in yen or else they will have to pay exchange themselves. Showing the US rate on their website is moreof customer service, so you don't need to convert it yourself and wonder how much it really is.
Ultimately, we won't get away not paying the exchange transaction fee.
Instead of paying in US dollars and take a hit from paypal exchange rate, pay the yen price directly with your credit card, my credit card gives slightly better deal than paypal.