Found a hidden button in the emperor's palace courtyard. However despite my best efforts I can't figure out what it does, and there is nothing on the internet I've found that helps either. Maybe you guys can help. Upon entering the emperor's palace area, head to the right. A guard is standing in front of a small pond with small tipping reeds. If you draw water to the center reed you will notice that a button is undepressed, and a sound is made like you unlocked something. Still have no idea what it is. Good luck.