Chaeyoung just made a friend in the weirdest way, but she got to admit that it is yet the best thing that ever happened to her ever since she moved into a new apartment: meeting Mina the ghost.

or

A MiChaeng AU based on this prompt I found from prompt generator: Mina is a ghost and she died in the apartment Chaeyoung moves to. Usually Mina is grumpy and possessive of the apartment and scares out anyone that moves into it but holy , Chaeyoung is cute, and Mina doesn't want her to leave.