永遠の0 (Eien no Zero, or The Eternal Zero)
Several years ago, Naoki Hyakuta wrote a best-selling novel about a brother and sister's search for the truth about their grandfather, an Imperial Japanese Navy pilot who died under undisclosed circumstances. The book describes many technical aspects of Japanese military aircraft and, more important, tells a love story that is timeless and haunting.
The Eternal Zero has been made into a film and was released in Japan on 12/21/2013.
Trailer at the link below: