The Demon Lord Is a Complete Fool

Synopsis: Tang Heng had just bound himself to the [System for Reaching the Pinnacle of Cultivation] when he was "forced to betray his sect" and go undercover. He never expected that his contact, whom he'd never even met, would die during a battle between the righteous and demonic factions. Unaware of what had happened, Tang Yan carried out his System missions while "concealing his identity" as an undercover agent in the demonic faction, for three years and then another three... Six years later, Tang Yan married the Demonic Lord's son, joined the family, and inherited his father-in-law's position and entire fortune. He was utterly bewildered. "When will this hidden mission ever end??? I'm already the Demonic Lord. Am I supposed to go undercover in my own base?" System notification: Host, please remember the rules of cultivation. Cleanse your heart, reform yourself, and become a new person. Cultivate immortality, not demonic arts, for everyone's safety. The System for Reaching the Pinnacle of Cultivation is at your service. This story is also known as Undercover Becomes the Demonic Lord, Still Has to Be a Double Agent / The Trash System Keeps Ruining Lives / Surprise, I'm a Dad: I Cheated on Myself Theme: Clear your name and reach the pinnacle of life