In a sudden twist of fate, he transmigrates and becomes Li Chenggan, the Crown Prince of the Tang Dynasty. Facing a tragic future, Li Chenggan, who has acquired a system, remains completely unfazed. Li Shimin: Chenggan, why did you rebel?! Li Chenggan: Please address me as Your Majesty, the Retired Emperor! Li Shimin: Chenggan! Li Chenggan: Retired Emperor! When Li Chenggan commands a million-strong army, Li Shimin is nothing but a Retired Emperor! When the dragon flag of the Tang Empire flies across the world, when the dragon flag of the Tang Empire begins to appear in other worlds, when the laws of the Tang Dynasty become the laws of all heavens, when Emperor Li Chenggan of the Tang Dynasty reigns supreme over all heavens, the Tang Empire stands above all heavens!