Max-Level Sword Immortal

Every time he dies, he carries his memories into a brand-new world. He has been reincarnated as plants and trees, insects, fish, birds, and beasts. He has been a beggar and a god. In this life, he is reborn as a human. He wants to decide when his life ends, so he picks up a sword and sets out to discover what being cursed him with a life that has no end. This is all he can do.