Leo Kataoka, 24, remembers watching ¡°Grave of the Fireflies,¡± Studio Ghibli¡¯s anime about the hardships of a boy and his young sister during World War II, in his ninth-grade civics class.

¡°It¡¯s not like I think about it all the time, but whenever someone talks about watching a film in school, I always think about ¡®Grave of the Fireflies¡¯ ¡ª it¡¯s vividly in my memories till now,¡± he says.

Many schools in Japan show the 90-minute anime as educational material to tell the emotionally grueling story of the boy, who has no means to prevent his sister from starving to death.