'Kiku-chan to Okami' is an adaptation of 'Grave of the Fireflies' author Akiyuki Nosaka’s short story 'Toshi-Oi Mesu-Okami to Onna no Ko no Hanashi' (The Story of the Old Mother Wolf and the Girl), which follows a girl and the wolf in the fields of WWII Manchuria who watches over her like a mother. (Source: AniDB)