Congrats!
The coffin room... is that the place where, if you look at mannequin in first-person camera mode, she turns her eyes at you in a creepy fashion? I remember something like that. I think I might've jumped at that part.
Anyway, it's been several months since I played the game, and now I'm really having a hard time recalling the details.

I looked it up, though, and came across this:
http://cameraslens.com/fatalframewik...ougetsu_Kagura
The relevant part is at the bottom, under "Disaster". People's souls would leave their bodies during the ritual, but since it failed, the souls didn't properly return to their bodies, causing the state known as Luna Sedata. Take a look at Sakuya's
Wiki page, as well as the page for the
Lunda Sedata (Getsuyuu) Syndrome, might answer a few questions. It did help me refresh my memory a bit.