Replay

One day, the protagonist, Park Woo-jin, is in a car accident and faces death. His last memory is of being taken to the hospital in an ambulance. When he opens his eyes, he finds himself in a place that doesn't feel like a hospital. Just then, his friend Dong-hyun enters. Huh? Why is Dong-hyun, who should be over 50, standing before me like a high school student?