It's not the exchange rate. It's 30 years of economic destruction and currency devaluation as the end result of horrific spending policies. If Japan doesn't right the ship, they'll sink into middle income territory over the next 30 years. Poland and Greece are now just slightly below them in GDP per capita - and Lithuania is above them (unthinkable circa the mid 1990s).

Realistically Japan is very close to being a second tier economy. It's quite plausible that Croatia and Latvia will pass them on GDP per capita over the next decade. 7-11 Japan would be relatively inexpensive for the citizens of any affluent nation, because Japan is so much poorer than it used to be.

7/11 is still 30-50% more expensive than the supermarkets, so irrespective of how affluent people are, it's a poor choice.

I used 'exchange rate' because not only is the yen weak, but the USD seems pretty strong - I guess it depends on where in the US you are from, but as a Brit, US feels expensive to me, Japan feels cheap, ergo Americans must find Japan even cheaper than I do.

Convenience stores have gotten more expensive but they've always been an expensive option in Japan. It's always been much cheaper to go to grocery stores or other such alternatives to get the same items.