Grave of the Fireflies

Japan, summer of 1945. Fourteen-year-old Seita cares for his younger sister Setsuko after losing their mother in an air raid and briefly staying with an aunt who treats them cruelly. The two siblings decide to live alone in an abandoned shelter near a lake, surviving on the meager resources Seita can obtain. Isao Takahata adapted Akiyuki Nosaka's autobiographical novel into the most heart-wrenching animated war film ever made.

Grave of the Fireflies is the saddest film associated with Miyazaki—though directed by Takahata—and one of the most devastating in the history of animation. It's not for children: it's about war, seen through children's eyes. It must be seen to understand Japan's past.