Grave of the Fireflies (Hotaru Na Haka), is a 1988 animated film written and directed by Isao Takahata. It is often hailed as the most powerful anti war movie ever made.

I was lucky to run into this very good discussion about the movie by Roger Ebert. It about nine minutes long and discusses a unique aspect of the story telling technique used in the movie called a pillow shot.

Roger Ebert on Grave of the Firelies and the “Pillow Shot”

I got some more information about this technique from this cinemaspace page

Grave of the Fireflies

Setsuko and the wonderful fireflies.

Seita and Setsuko by the riverside.

Magical Night of Fireflies

Setsuko and the Umbrella