For John, BLUF: Japan is still a little rigid, culturally. Nothing to see here; just move along.
If you like your name you can keep your name, except in Japan. From The Old Gray Lady we have this item—"Japan’s Top Court Upholds Law Requiring Spouses to Share Surname".
There is a lot of freedom for people in these United States. Not perfect, but better than many places.
Regards — Cliff