After Talking About Tianhu's Start, How Did He Become an Undercover Agent of the Demon Sect?

At the beginning, I traveled through time and became the righteous genius and the prince of Zhenbei. Before I had time to enjoy the embrace of my childhood sweetheart, the daughter-in-law, I awakened my undercover memory! Who would have thought that this "natural sword bone" that shocked the past and the present was actually a forbidden magic from the Demon Sect that burns lifespan? The poisonous heart-eating Gu in the body is about to break out in five days. The master of the transformation stage is right outside the door, and the demon king's death order is even more extreme: let me, with a golden elixir in the early stage, go to the prison to rescue the witch? Starting in a hellish sinkhole, there is no system, only the top acting skills trained by social animals! ! !