Barefoot Gen

Barefoot Gen is a 1976 Japanese war drama film, directed by Tengo Yamada based on the Japanese manga series of the same name. The film is set in 1945 and tells the story of the six-year-old boy Gen Nakaoka, living in Hiroshima around the time of the US atomic bombing of the city.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.