Grave of the Fireflies
Time Out says
A janitor rifles through the possessions of a recently deceased boy and throws out some ashes and bones from a tin. These remnants spark to life as the spirits of 14-year-old Seita and his younger sister Setsuko, who were caught in the devastating attacks on the city of Kobe during the final months of the Second World War. In flashback, we witness the anguish of Seita and Setsuko as American bombers blitz Kobe, transforming the city into a flaming hell, which ultimately claims the life of the children's mother.