Other people's time travel systems are all about killing gods, but you just want to cling to your life. But the ability of "life span trading" made you the most conspicuous target in Zhu Yuanzhang's "Great Purge". So, you decided to put on a vest for yourself - "show your holiness" in front of the civil and military officials of the court, take action invisibly, revive the critically ill Queen Ma with a snap of your fingers (actually deducting ten years of Sapphire's life), and then create "Nine Heavens Black Iron" (titanium alloy) out of thin air.
From then on, you became the most mysterious "National Preceptor" in the Ming Dynasty. During the day, you pretended to be a fool in front of Zhu Yuanzhang; at night, you hid in the palace and used the modern management books exchanged by the system to teach Prince Zhu Biao how to run the country efficiently. You must personally push the Ming Dynasty's national destiny to its most glorious peak.
It looks good. The author will update soon.