From about September to Feb the Yen was actually one of the strongest performers and gained on the Dollar. If you talking about a 30% loss thats more likely their stock exchange but i dont believe the yen/dollar rate would have any bearing.
No yen vs dollar. If you look at sony they manufacture in Japan - yen dominated. So September the yen was at 125 or 130 vs dollar.
Now it have gained against the dollar and trade 95 - 100.
So Sony get 25 % less for the same console sold in the US / uk euro
as they did a few months ago.
Same with nintendo - they just increased the price in Pounds because the pound now trade 20 % less than a few months ago.
Take our rand as an example, we were at 7.5 to the dollar and now are at 10 to the dollar, So the xbox went from R1800 to R2400 in price.