Imagine a world where history itself has been rewritten, leaving you as the only one who remembers what was lost. That's the startling reality facing Kai in *Naze Boku no Sekai wo Dare mo Oboeteinainoka?* Once, humanity stood triumphant, led by the legendary hero Sid, after a great war against five powerful races. But in a blink, Kai finds himself in a twisted reflection, a world where Sid never existed, and humanity was crushed. Now, dragons and demons rule the land, and Kai is a forgotten ghost, unknown to everyone he once knew. His desperate fight for survival takes an unexpected turn with the arrival of Rinne, a mysterious girl who might hold the key to unraveling the altered timeline. Thrust into a world devoid of its champion, Kai must rise to become the hero humanity desperately needs. He inherits Sid’s sword and martial arts, preparing to challenge the monstrous races that dominate the earth. This is a story of courage against impossible odds, of reclaiming a lost legacy, and of one young man's determination to restore the world he remembers. Will Kai succeed in rewriting destiny, or is he doomed to remain a forgotten anomaly in a world that never was?