I have a funny feeling a lot of this discussion has been covered in another thread.
There has been some limited discussion of bringing in tourist prices in limited places as a way to combat over-tourism.
I don't see discriminatory pricing combatting overtourism (whether this is cheap for Japanese vs "expensive" for foreigners, or free for Japanese and costs for foreigners)... at least right off the bat.
The simple reason is because consumers will simply shift their minds to accepting the cost of entry as part of their budgets. While other costs like accommodation aren't exactly cheap as such, for the majority of the tourists coming in, most things are still cheap. A few increased prices in entry to places won't make a dent.
Increasing prices dramatically or introducing a quota (even a quota limited to foreigners) will be a better attempt at curbing overtourism. For example, a place may only allow 50 foreign tourists per hour - once all booked out, no more entries, but no limit on Japanese entries.
That said, any increase in prices (even for foreigners only) can mean more revenue (curbed overtourism as a result would be a bonus), so it's not outwardly a ridiculous idea.
I believe in some way, the Japanese were not prepared for the issues that would arise from overtourism (if that is indeed what is happening now). Some may say it was naive of the Japanese to not accept the bad with the good. Some may believe it is a good problem to have (i.e. think of the opposite), but when insular Japanese have to put up with insolent and inconsiderate foreigners, it cuts close to home.
I wonder if it's out of place to advise: for the savvy and maybe adventurous traveller, a better idea to visit Japan is to consider the much less trodden places. I went to Kanazawa and Takayama one year; another I visited Sapporo (OK, that's well touristed), Hakodate and Yamagata. To be fair, some of the traditionally "off the beaten track" places are likely not any more, e.g. Himeji, Kobe (to some degree), Okayama, Fukuoka (Hakata), Sendai and Aomori.