The Zon Ghost is a deleted ghost from White Day: A Labyrinth Named School. It was eventually removed for unknown reasons and it's textures were leftover in the data files.
Not known about this ghost but there are 4 variations of it:
The first one seems to be similar like Haunted Head Ghost but it has different designs.
The second one is the similiar like the first one but more blurred one and plain designs.
The third one seems to wear a lab coat and a doll mask (?).
The fourth seems to be revealing and wears traditional clothes (?).
It is also unclear what "Zon" stands for.