I think you're severely exaggerating the drop of other currencies against the Yen:
http://finance.yahoo.com/echarts?s=USDJPY=X#symbol=USDJPY=X;range=2y
http://finance.yahoo.com/echarts?s=EURJPY=X#symbol=EURJPY=X;range=2y
I see more like a 20-25% drop, not 40-60%.
My Mario Kart Wii friend code: 2707-1866-0957