Traveling back to June 3rd of the ninth year of Wude, Chen Huai'an falls under the command of Crown Prince Li Jiancheng, foreseeing the Xuanwu Gate Incident on the very next day. Failing to persuade the Crown Prince, he simply drags Wei Zheng to imprison themselves in the celestial prison, accurately predicting in advance that Li Shimin will recruit prisoners to raise troops. After the incident, relying on his foresight, he gains Li Shimin's heavy trust, enters the Hongwen Pavilion to teach aristocratic scions such as Li Chengqian and Cheng Chumo, breaks the class prejudices of scholars, farmers, artisans, and merchants, improves the curved-shaft plow, Mo Dao, and horseshoes, and brews distilled liquor to accumulate massive wealth. While teaching youths the path of saving the world, he assists Li Shimin in purging Pei Ji and preparing to resist the Turks, quietly laying the foundation for the Zhenguan Prosperity with the leisurely identity of a schoolteacher.