This film was initially distributed with Meu Amigo Totoro (1988) because it was the only way that Miyazaki could have been able to make "Totoro." The reason being that the original film pitch for that film was rejected, so they pitched a double feature with "Grave of the Fireflies," and the project was eventually backed financially by the original writer of the book on which "Grave" is based. It often was overlooked as a film because whenever "Totoro" was screened first, people were left happy and did not wish to be saddened by "Grave" afterward.
In South Korea, the release of the movie was postponed indefinitely because of the concern that the movie somewhat justified Japan's role in World War II.
Produced concurrently with Meu Amigo Totoro (1988). Many of the animators had trouble remembering which film they were animating.
If you brighten the poster of the film, some of the lights are not fireflies, but incendiary bombs from a B-29 bomber.