I’ve been in Japan the last 4 years using my T Mobile plan. Just make sure to set cellular data to your local line and don’t enable data switching. You should not get any warnings. I also pay $140 for 3 lines (Magenta Max plan I believe).
Yessir! Likewise than you for keeping us updated through your thread. You applied a day later than me and Lee so I’m betting you will be approved Monday!