Japan does have host bars, where for about JPY 15000, you can take one & have an hour in bed, or whatever takes your fancy. To be clear the 1 hour is fixed, but they will do anything specified on their page in the catalogue, which is generally all the usual options. And with a smile.
On the foreign exchange issue, the 10 year data JPY-GBP rate shows how far things can move.
Current rate = 139.6
Highest rate = 249 2007
Lowest rate = 117 2011 ie less than half the 2007 rate.
Actually even in 2008, the lowest rate was about 126, so almost halving in very little time.
I make 2 Conclusions
1 Anyone holding one currency and spending another needs to consider that very large currency movements are possible. To mitigate this, they could consider investing in overseas assets to reduce the risk.
2 Gordon Brown really made a pigs ear of running the show.