It would be extremly funny if there was no enemy stand and Usagi just hallucinated it because seeing a corpse didn't do any good to his ongoing mental meltdown. But it's likely an enemy stand.
It started from hallucinations. But then people psy-oped themselves into becoming actual spooks after death and it started sort of a self-perpetrating cycle.
But we have a particular case on our hands in which it did exactly that. Bullying can take many forms, but what we witnessed right here was a conspiracy with aim to destroy good name of a person with a lie. For things said person had no controll over. His biggest fault was not being educated in...