When working out how much to charge for the prints, our calculations are all done in Japanese yen - that's where we live and work. So the yen price for these prints is the 'base' price, and the others are calculated from that.
But because currencies fluctuate over time (do they ever!), we must sometimes make adjustments to the prices in other currencies. We have no idea when such changes will happen: perhaps tomorrow, perhaps not for months.
The price that will be in effect for the year of your subscription is the price showing on the subscription page at the time you send in the form. We will guarantee that price for you for the 12 months, even if your chosen currency falls against the yen.
If at the end of the 12-month subscription, you decide to continue for another year, the price for that will be whatever price is then current (we will of course let you know at that time ...)