The Melody of Oblivion(2004)

The Melody of Oblivion is an anime series set in a world where demons won a devastating twentieth-century war against humanity. Monsters now rule in the shadows, their presence a constant threat yet largely concealed from ordinary people. Young Bokka becomes obsessed with uncovering the fate of the legendary Meros Warriors, the brave fighters who once stood against the demon invasion. As he searches for answers about these lost heroes, Bokka discovers that the past holds dangerous secrets that could reshape his understanding of the present conflict. The series blends mystery and dark fantasy as Bokka's quest forces him to confront uncomfortable truths about the war, the warriors, and the hidden world of monsters that surrounds him.