I know this thread is mostly about the physical stuff, but maybe someone knows.
Amazon JP sometimes doesn't show me certain "adult" (at least marked as such) Kindle manga such as e.g.
https://www.amazon.co.jp/dp/B07YX26HQL
I can see it if I'm not logged in and under a Japanese VPN, but I get a 404 when I'm logged in even though my account is set to Japan and my default address is set to Japan and I'm using a VPN. What should I do?
Ironically I can see the physical version of the same thing just fine.