Horror Short Story | Myself at Midnight

In high school, a rule circulated among students: at midnight, if you called your name three times in front of a mirror, you'd see your future self. He scoffed at it, but his roommate's urging made him try it anyway. "Shin, Shin, Shin." There was no change in the mirror. His roommate burst out laughing, and Shin laughed too, turning over and going to sleep. In the middle of the night, he woke up needing to pee. As he got out of bed and passed the mirror, a glance from the corner of his eye saw the person in the mirror still sitting on the bed. He whipped his head around. The 'Shin' in the mirror was looking down at him, slowly raising a hand to point at him, his lips silently forming words: "Why are you still here?" Shin rushed to the bedside and lifted the covers. Lying on the bed was himself. His face was pale gray, his eyes wide open, the corners of his mouth slightly upturned. And the 'Shin' in the mirror slowly climbed off the bed, walked towards the door, turned back, and smiled at him: "Thanks. I can finally leave now." The door closed. Shin stood frozen, looking down at his hands—so transparent he could see the floor. The next morning, his roommate couldn't wake Shin in bed. When the ambulance arrived, the doctor shook his head, saying he had passed away during the night. But his roommate remembered hearing someone open the door and go out around 3 AM, humming a tune. That song was Shin's least favorite.