Hello, everyone! I recently got married with an American citizen and got green card. So the green card is under my new last name, although my japanese passport has my maiden name on it. I have to renew my passport before I go back to japan this October, and I already bought a plane ticket. Now, when I renew my passport, will it be under my new last name? Or would it go under my old last name since I have made no changes in japanese birth certificate (koseki). I am worried because I have already purchased my ticket back to japan under my old name, and the name of the ticket would have to match the name on your passport. I would greatly appreciate any advice on this. Thanks you so much for your time! :)

As far as I know, no one makes name changes on a birth cert. because it carries the name you were born under. Your passport reflects your name as it is today, your passport is signed with that name in place. I wouldn't worry too much about what name you purchased the ticket under.

This is not a problem at all. You might have to have some proof that these two names are of the same person.