I wonder if Japan will react to Apple's newly announced conditions for them, where you can use IAP and pay 15 or 26% commission, or not use IAP and pay 10% or 21% commission + your payment provider so the prices are effectively the same either way + other terms like those in the article, which basically means you get nothing but headache for not using IAP.
This tactic is specifically illustrated in Japan's compliance hypotheticals (on page 51):
> Hypothetical Scenario 73: A designated provider, when individual app providers use alternative payment management services, demands fees or places financial burdens at a level that creates a high likelihood of making the use of such services practically difficult
https://www.jftc.go.jp/file/MSCA_Guidelines_tentative_transl...