The soul of a person who falls into a coma will come to a place to take an exam. If he passes the exam, he can wake up in the human world. A few years ago, "GROZA" passed the exam, but a bug in the system caused them to disappear. Only they knew the secret of the system at that time - a new batch of candidates came to take the exam, and two of them were arranged to take the special exam of the system. Dislocated in time and space, they met another completely different version of themselves.
Concept: The world of mortals is ever-changing. You are not young now, but you are young then.