I think they were in the loop until their memories burnt or… they became a living zombies, unable to make sense anymore. That's why when next day came, they don't remember anymore what torture they had to go though.
So it wasn't a nameless malice, it was a neck-leash malice :haa:
Also check out mangaka's other not so famous manga, which is better, I would say…
A Suffocatingly Lonely Death
It got a live version adaptation recently