When everyone else transmigrates with a System and becomes unstoppable, all you want is to stay alive. But your ability to trade lifespans makes you the most conspicuous target in Zhu Yuanzhang's "great purge." So you decide to take on a secret identity. In front of the entire court, you put on a display of divine power, striking from the shadows to restore Empress Ma, who is on the brink of death, with a snap of your fingers. In reality, you took ten years off Lan Yu's life. Then you conjure "Nine Heavens Mystic Iron" out of thin air. It's titanium alloy.
From then on, you become the most mysterious "Imperial Preceptor" in the Ming court. By day, you put on a show of magic and mystery before Zhu Yuanzhang. By night, you slip unseen into the palace and use modern management books exchanged from the System to teach Crown Prince Zhu Biao how to govern efficiently. You intend to personally lead the Ming dynasty to the most glorious heights of its national fortune.
It looks good. The author will update soon.