I think there is an episode of The X-Files where a monster or an animal, I don’t remember exactly which, gets turned into a human monthly like a reverse werewolf. I remember them being horrified about their condition.

We talking in the anime or in the manga? Cuz at least in the manga it makes a bit of sense. Roger gets haunted by a Schwarzwald apparition twice, even before he gets exploded in the Big Duo. And the Lost Memory has a ghost presenting as living person too.