Grave of the Fireflies

Alternately known as Tombstone for Fireflies, Grave is a very somber film about the struggle of two children to survive during World War II. Seita and his younger sister Setsuko are left to fend for themselves when their mother passes away from severe burns inflicted by the American fire-bombing of their town. Their father is serving in the Japanese navy, but the children have not heard from him in a long time, so Seita and Setsuko try staying with a distant relative. However, Seita doesn't get along well with this relative and decides to leave, taking Setsuko with him, to live on their own. (official distributor synopsis)