The Melody of Oblivion

The Melody of Oblivion (2004) is a animation, action & adventure, sci-fi & fantasy with 1 season, rated 6.4/10.

After a war occurred in the 20th century between humans and demons. Since that time, the monsters rule the world in fear but keep relatively hidden from public view. A boy named Bokka ponders the past and wonders what became of the Meros Warriors who defended the world so bravely against the demons.