From the Start, I Become Wu Zetian's Man

After transmigrating to the Tang Dynasty during the Zhenguan era, Li Zhi becomes Li Shimin's ninth son. From the start, he's just four years old and carries the Mischief-Making Demon King System. What are carrier pigeons rushing a hundred thousand li? Roast them! What are imperial edicts? Draw on them! What is Li Er? Mess with him! Li Er: Wang De, how are Zhinu's studies coming along? Wang De: Your Majesty, Kong Yingda has already become Prince Jin's student! Li Er: What? Wang De: Yan Liben and Wang Xianzhi soon followed, and they, too, paid their respects to His Highness Prince Jin as their teacher! Mastering music, chess, calligraphy, painting, swords, spears, and every art of war, I can rule the realm with both pen and sword. I, Li Zhi, consider myself second to none. Who dares claim to be first?