The Exiled Sword Bone: I Slay My Master to Walk the Righteous Path

In a chaotic xianxia world overshadowed by the prophecy of "Killing the Master to Destroy the World," Lu Chen, an orphan of a massacred family born with a natural sword bone, is imprisoned by his enemies with iron chains piercing his shoulder blades. As bizarre murders occur one after another, he is forced to descend the mountain with his master, trapped in a certain-death situation amid public scorn and surveillance. Awakening a Karma Deduction System, he uses his lifespan as bait to replay the scenes of the murders. Each broken chain brings him one step closer to that bloody counterkill. The whole world awaits his master-slaying, but he intends to overturn heaven's mandate! — Description from novelcodex.org