That goes against everything I've ever heard on the subject and I don't recognize this site. Also if it was a carrier reason, wouldn't the sound appear if you were roaming in Japan? It doesn't.

You haven't heard of Buzzfeed Japan? You're welcome to try to find the law though.

> Also if it was a carrier reason, wouldn't the sound appear if you were roaming in Japan? It doesn't.

If it was geofenced you could disable it by putting it in airplane mode, so it's by purchase country instead. (On recent phones it does turn off if you leave Japan though.)