Boukyaku no Senritsu

During the twentieth century, humanity waged a devastating war against monstrous entities and ultimately lost. As a new era began, the memories of that catastrophic conflict faded entirely from human consciousness. Monsters now govern the world from the shadows, allowing society to maintain an illusion of ordinary life while people harbor a quiet, pervasive dread. In their desperation, some individuals attempt to appease these unseen rulers by sacrificing children, whereas the majority simply choose to ignore the horrifying reality unfolding around them. Yet, a defiant few refuse to surrender to despair. Known as the Melos Warriors, these fighters continue the ancient struggle against the monsters. Their ultimate hope lies in finding the Melody of Oblivion, a mysterious girl prophesied to hold the key to humanity's salvation. When a young man named Serina Bocca unexpectedly awakens to his destiny as a Melos Warrior, he is thrust into this hidden war. Leaving behind the fragile normalcy of his former life, Serina embarks on a perilous journey to locate the Melody of Oblivion and restore hope to a world living under the weight of forgotten terror.