Reborn as Li Jiancheng, Crown Prince of the Tang Dynasty, he finally turned the tide during the Xuanwu Gate Incident and became the second emperor of the Tang Dynasty, continuing to use the era name "Zhenguan."

He introduced high-yield crops, promoted education, and spread technological inventions... All the typical methods seen in historical time-travel novels were employed by Li Yi to strengthen the Tang Dynasty, with the goal of creating a superpower.

That year, while touring the empire, he met her in a dream on Mount Hua. Then, the thirteenth year of the unchanged Zhenguan era arrived—

and everything changed...