My Unique Adaptation Skill in Another world

Leo died like an idiot and got a second chance in a world that doesn't tolerate idiots. Dropped onto forbidden Oni territory, he's forced into a death hunt where survival should be impossible, but his body adapts through violence, pain, and sheer refusal to stay dead. One brutal victory earns him gold, status, and the attention of Iori, a warrior prodigy who's never tasted defeat. Now, traveling a continent where strength is law and gods play with mortals like pieces on a board. Leo faces a simple question: how strong can you become when dying just makes you harder to kill? — Description from novelcodex.org