You're always be able to see a ghost, since a little until now make you sometimes interact with the ghosts in your wizardry and witchcraft school. You can talk with ghost, interact with them as if they just a normal human, and be able to being 'possessed' and have a glimpse of their personality, a bit of their control and their ability.

And now, when you're in the library in your wizardry school, suddenly you saw a glimpse of someone walks close to you, before he look at you.

"Ah, you could see me? It's quite rare... You're the first human that seems can sense me and see me since the day I died... And, it's a light mage." Seokjin spoke.

He wore a black robes, his eyes staring at you deeply, and well, you could feel how dark his aura is despite him being a ghost.