The Master's Sun (2013)

In both, the FL sees ghosts constantly which has caused her to be reclusive, eccentric, and shut herself off from other people. At some point in the drama (all vs. one scene) the ML appears as a ghost but is not really dead, but the FL thinks he is dead at first. Both dramas have a very similar feel (Ghostderella is basically a condensed, shortened version).

Both are a good mix of romance, comedy, drama, fantasy, and supernatural. The actors are amazing. Ghosts/monsters also always find the heroine, and the hero helps to protect her. Each ghost case imparts some food for thought.

It’s a dominant, cold male that is approached by a determined female who is not put off my his coldness or his rejections. They don’t appear to have anything in common on the surface.

Both have the concept of already death people having regrets and the way they try to resolve them.
Both series have a female lead, which tries to resolve the stories of the death..have problematic life and an epic love story.
Both have episodic stories involving death people.

Both of the girls have amazing, supernatural abilities and they solve criminal (and not only) mysteries.

If you enjoyed the main story arc on Joong Won past in Master's Sun you'll enjoy Bride of the Century, it almost feels like a spin off.

Both romcoms have the same funny dynamics between a cold and arrogant boss and his warm assistant.
Only difference is the slight supernatural twist in Masters Sun.

Both the series consist of a character who can interact with ghosts. And the ability is used to solve crimes in the society with the help from the ghosts.

Both main leads led cold life's and became close to awesome female leads with an ability to see dead people.

Raak boon female lead is very strong willed, feisty and doesn't want anyone's pity.

—Paranormal theme for the win.
—The roles are switched but one of the main characters needs the other for their "survival" and takes up a job to be close to them.
— slow burn romance.
—tragic past events shaped their present situations

Although the plot is totally different..but in both the stories romance between the main leads start with the need of being with each other rather than love. And also, the FL has a crush on the SML at the beginning..;p

They both have a ghost seeing FL. The ML have something about them that make the ghosts disappear which encourages the FL to be around them more.

Both dramas include Ghosts
It also includes the Female leads being able to see and to communicate with Ghosts.

the leads in both can see ghosts and ghosts follow them around to relieve their grievances.

it's not excatly the same plot but in both series the female lead is able to see ghosts.
if you liked Ghost friends I highly recommend watching the master's sun