I Can See Ghosts with My Left Eye: My Ghost Bestie Knocks at Midnight

[Ghost hunting + System + No romance]

When Qiao Xingchen was seven, an accident changed her left eye in some unusual way.

For years afterward, she wore special glasses. Then her best friend suddenly met with an accident, turning Qiao Xingchen's life upside down as well.

Her best friend became her life-bound ghost.

What happened to the ghostly best friend who knocks on her door in the middle of the night?