To save his younger sister, who suffers from a deadly cold poison, the young Chu Ning risks his life to join the Demon-Suppression Bureau. During a life-or-death trial, he fights desperately to slay a green-scaled snake demon, unexpectedly activating the Ultimate Demon-Slaying System and obtaining the Nine-Yang Divine Body. From then on, Chu Ning slays demons and monsters and eliminates evildoers, rapidly increasing his cultivation and repeatedly breaking through in saber techniques and movement skills. In a short time, he rises from a lowly newcomer to a top-grade demon-suppression officer. Facing sinister forces, evil cultivators, demon kings, and sects that make things difficult for him, he carves a path forward with his blade and fights to protect his younger sister, crushing every obstacle as he rises to power on his journey to slay demons and eradicate evil.