Naze Boku no Sekai wo Daremo Oboeteinai no ka?

Humanity’s victory in a war against five rival races is erased from the world’s history, leaving Kai as the only one who remembers it. In the rewritten world, dragons and demons rule the land, and the human hero Sid has vanished. When Kai encounters the mysterious girl Rinne, he decides to challenge this altered fate. Armed with the hero’s sword and martial arts, he faces the dominant races in a world where humanity has no heroes.