URGENT: Movie title

Oh my im going insane!! I kupanda this movie at costco last night that i really wanted to watch but my Dad wouldn't get it for me:( but now i cant remember the name! I know its about a girl who lives in Japan after world war 1 au 2. She meets a boy an thats all i can remember. Please help! I'll shabiki whoever can give the right answer. They will also get props:)