I’ve done the same thing for discovering cheaper billing profile on many services, e.g. Netflix or whatnot. Never thought to document it.

Finding it is a bit easy, processing the payment sometimes is geo locked by an account in that region (google/android) or having a form of payment in that country. Japan usually is paypay or a credit card with the BIN issued in Japan. There are many local payment providers though that do allow a foreign credit card so in the an China example:

Download WeChat/alipay, add foreign credit card, Change region, ????, profit.

It does get easier and very inexpensive if you do have foreign residencies and you can really rework purchasing.

Spotify for example is not sticky, but they are aggressive on if they aren’t sure you’re region specific to lock you into a monthly plan before allowing you to switch to yearly.

~ There was also great arbitrage for a while on providers that allowed switching to turkey residency and allowing foreign credit card billing but this ended due to the currency instability and now most software sellers anchor it to another region. ~ Also you’d be surprised about the minimum requirements to open up financial accounts in foreign countries. Linepay is pretty much open, but kinda sucks (Japan, Taiwan and Thailand) and it seems the LINE developers are maximizing at destroying their app and audience while WeChat and Alipay are amazing for what they are in general.