In a crumbling world, Ethan Maxwell Blackthorn stands alone. With his "rewind" skill proving useless, he survived like a coward for a decade. But as the monstrous Last Boss looms, Ethan knows it's all over. “You weaklings! What sort of heroes are you, losing to the big guy just like that!” Just when all hope seems lost, Ethan’s death triggers his Rewind skill, sending him 24 hours back in time. Although confused, he realized this godsent opportunity. “Great, now I can survive!” Yet no matter what he tries, the outcome is always the same. Day after day, he’s caught in a brutal cycle of death. Despair gnaws at him, but after countless failures, something snaps inside him. Fed up and desperate, Ethan vows to change the outcome. “If they can’t do it, I will kill the boss myself!” After millions of deaths, endless suffering, and relentless trial and error, Ethan finally conquers the Last Boss. His victory is hollow, however—there’s no one left to save, no world left to live in. And then, as if mocking his efforts, more Last Bosses appear over the horizon. Humanity’s last stand was in vain. But just as all hope fades, a revelation strikes: "No Cost," the reward for his victory grants him unlimited use of his Rewind ability! With this, an idea popped in his weary mind. “Can’t I just go back to before the apocalypse began?” Armed with a chance to rewrite history, Ethan starts anew, determined to be more than just a survivor. “And if I’m going to play hero,” he resolves, “I’ve got to do it thoroughly!” Aim high! Zero Casualties in the Apocalypse!