@unseenjapan This sounds like a terrible idea. First, if it does happen, I don't trust them to phase out the system if the yen recovers. I also doubt it could be done in a way that wouldn't hurt people from less developed countries, especially if their currencies aren't as strong as the USD, EUR, GBP etc. It's also not as if every currency is experiencing historic highs in their value towards the yen. I looked at a few, and despite rising in recent years, the value of the Brazilian Real to the Yen is 32% less than it was 10 years ago. The Indian Rupee and Malaysian Ringgit are better at +7.32% and +2.17% compared to March 2014, but they're still lower than their peaks in late 2014.
I think discussing whether or not exchange rates are unfair is a waste of time. It's not as if there's a natural value that they should always return to, and I never heard anyone discuss lower prices for tourists when the yen had more value in the early 2010s. Compared to the GBP, I don't even think the Yen is particularly cheap at the moment. There were times when it went as high as 232 yen per pound when I first visited in late 2006.