Standing Alone

When they first met, he opened the door for her. She glanced at him, took two steps back and looked up at the house number, then frowned in front of him and pursed her lips, taking out her mobile phone... Unexpectedly, he looked at her and smiled: "You must be Gao Zichen's teacher. You're right. Come in." After staying for a few days, he opened the door at random, but the person who came in disturbed him...