I find that librarian guy suspicious. He knew about Kouichi's mother and was fascinated about learning about her death. And plus, I have a feeling he knows something about Mei since in an earlier episode, he requested Kouichi to leave the library whilst looking over Mei, as if he knew she was there but didn't want Kouichi to know, or to speak to her.
Well, another death has happened, but I can honestly say that at least it wasn't as grusome as what the others have been. And who knows, maybe this 'curse' wasn't the thing that killed him, he did have a heart condition, perhaps the recent events and orders he had been giving just put to much stress and pressure on him.
And now it appears that Kouichi is being given the silent treatment just like Mei. These students must be terrified to have to resort to things like that. But now at least we know that Mei really does exist...right?
This episode showed that she does seem like a normal school girl.