Well let me just make sure we're thinking of the same movie.
Is this the one where
a) Brother and younger sister who's mother? is dead, father is fighting in the war.
b) Living with the Aunty during this time. Aunty hates them.
c) In rage Brother and Sis run away from home and live in a cave, Sister gets sick and dies. ;_; ;_; ;_;.
d) Their home town gets fire bombed.