It is said that after Nuwa successfully created the world, she observed the human world for hundreds of years and lamented that no matter how smart or stupid human beings are, they can never be worth the word "regret". In order to give humans a chance to make up for their mistakes, she left behind a spell called "Xinmei". It is said that as long as you possess this spell and cast the spell according to the spell, you will have the opportunity to go back to the past or go to the future and change the things you want to change. However, because the cost of the spell is too terrible, even those who possess it may not dare to try it. Over time, this spell slowly disappears from the world. Some people say that the person who once owned it hid it in a safe place, while others say that it was destroyed. But the only thing that is certain is that it has not reappeared for hundreds of years...