Noah Oakley, a genius of the Wardens Bureau, is framed by powerful nobles in his previous life, leading to the execution of his entire family. Just before his death, he activates the Life Simulator and is reborn at 16, carrying 15 extra years of lifespan. With only his younger sister, Melanie Townsend, by his side, Noah vows to change their fate. When the ruthless Chris Dalton kidnaps Melanie to offer her as a sacrifice to the Lamb's Mercy, Noah burns through his lifespan to strengthen his body, defeats his enemies, and uncovers the cult's accomplices. Armed with a broken sword, he ventures into the mountains to slay fiends and earn back precious years of life. Along the way, he meets Cara Townsend, masters powerful martial arts, breaks through to the True Steel Stage, and takes on the Lamb's Mercy in a series of fierce battles. But when he returns home, he discovers that Melanie has secretly taken in a demonic cultivator and begun practicing dark arts herself. To uncover the truth, Noah conceals his true strength and joins the Whale Syndicate. Sent to Everett Manor to slay a Willow Fiend, he follows the trail to an abandoned silver mine, where he exposes the horrifying truth behind the mining disaster: it is part of an Evil Deity Ritual orchestrated to summon the Great Shadow Sovereign of Shadow Ridge.
