Childhood Days aka Shonen jidai

Bombing during World War II resulted in whole urban populations fleeing to the countryside, and this created a meeting of urban and rural cultures. Shinji (a young boy evacuated from Tokyo) and his new schoolmates (who are villagers) don't exactly know what is going on in the war. They see the B-29 bombers and the glow of cities on fire, but the problems of being separated from one's mother and surviving among one's peers loom larger than international politics.