Just back from Japan. Was pleasantly surprised by ability to use cards and tap almost everywhere and no DCC In a couple of museums and a hotel I was offered the option of USD vs JPY even after tapping, but it was clear and I was able to select JPY without issue on the screen. I don't think I was shown the exchange rate, just the USD vs JPY amounts and had to select 1 or 2 to pick. Would showing the conversion rate be required? Maybe I was moving too fast.

ATM at post office did not even offer or attempt DCC. For larger amounts in a couple of restaurants and a hotel I was asked to insert and sign, but otherwise simple tap did the job with Visa or AmEx. I did notice that the machines where I was offered DCC looked exactly like the machines where I wasn't. (Big, black, sorry didn't get a pic.)