Isn't this just proof that Japan needs to let go of it's biggest barrier to growth? By which I mean it's non-existing immigration?
I've been recently to Japan and despite my fears Tokio was a really affordable place (leaving out the hotel prices of course). I thought this was due to the lack of growth and the recent quantitative easing and other government measures. Measurements that seem to be failing at the moment (thus the negative rates).
So cheap Tokio-Sushi is nice for European tourists, sure, but just a sign of how much growth Japan has lacked over the past years/decades that it suddenly becomes a tourist destination.
In contrast to that: I could imagine Japan, with its still high quality of living and modern, orderly society as a real draw for young and skilled talent from abroad if it were to open it's borders (and society).
Think about it in the terms of Gentrification: It's an artificially undervalued "part of town". One which value and (currently) cheap prices would sureley be appreciated by the pioneers this country needs.