She, a modern killer, once traveled through time and became an unpopular princess in the palace. He, Lord Tianshui, has been waiting in the mortal world for thousands of years, just to beg her forgiveness and return to him again. When they meet again, he knows her, but she doesn't know him. He accepted her as his disciple, taught her magic, and stayed with him for many years before she fell in love with him again. When she finally regains her memory one day, will she forgive him and return to him? Or still can't forget the hurt in the past and feel like strangers? What kind of entanglement happened thousands of years ago, and what are her identities with him? After going around in circles, many years later, she and he were under the pear tree on Moshang, and he said with a smile: "Che'er, I'm back."