These messengers are a group of unlucky people involved in supernatural events.
Yunming doesn't want to stay on the first floor. The easiest way to send a letter quickly is to tear it up before the time comes.
According to the law of ghost post office, a person can tear three letters at most.
Because by the fourth letter, no one could bear the ghost.
If you want to go upstairs, you need to send three letters. There are three letters on the first floor. The building has five floors and seven rooms on the first floor. It is a team.
Going upstairs is like screening.
This kind of screening can screen out waste, retain elites, and screen layer by layer