Read in the 1980s – 90s. Book follows a young girl in the US after WW2 where US loses the war. The Japanese take over the US and we follow this girl as she is forced to live under Japanese rule.
Stump the Bookseller
New format, same book stumper solving.
Live in Infamy by Caroline Tung Richmond.
This one is too new, but maybe it will help jog someone’s memory? It sounds just like the one you’re looking for.