It's so Cold That I Don't Know That the Warmth Has Arrived

It tells the story of the heroine returning to China to study, but her grandfather asked her to let her grow up on her own. He also gave her something and told her about a person, saying that if she had any difficulties, she could go to him and use that thing. In the process of getting along with the heroine, the heroine becomes more and more strange. The hero thinks that the heroine is the girl he knew when he was a child, but he doesn't dare to believe it. Finally, he slowly understands that it doesn't matter if she isn't. The story slowly reveals the puzzles and scars on the heroine's body. She wants the people around her to be happy, but she can't do anything. She is sensitive and weak, and even has divergent personalities. Her memory often disappears and she suffers from mental illness. She wants to escape, but she understands that she can only survive by getting out, which will only hurt others.