My Fake Brother-in-Law Is the Crown Prince

I transmigrate to the Tang dynasty in the sixteenth year of the Zhenguan era. Because I look just like the crown prince's brother-in-law, I'm locked in a cellar to serve as his double. From the start, I kill the man and take his place, stealing his post in the Imperial Bodyguard Corps, his house, and more... I don't know what it means to hold office in a region and bring prosperity to its people. I only know that what's mine is mine: you can't touch my money or lay a finger on my people. Otherwise, I'll show you just how much damage a little abuse of power can do.