About my last blog entry, well I actually have a new theory now
It's believe that Morishige jumped out the window and died, committing suicide, after finding out about Mayu's death. But I have a new theory. I believe that Mayus' spirit brought him to death. It would make sense, as most of the spirits in the school are controlled by Sachiko. And the fact that Morishige had no marks on him in Book of Shadows.
So Mayu's spirit killed him. That's my theory. what do you guys think? ((PS: The Manga of Blood Covered was different from the game. The game in cannon, while the manga is far from it. So his death may be different.))