So the culprit is emi?

Hmm emi head is cut off and one of the corpse is pretending death.

but only emi's head and the crazy girl missing.
But so far all the chara have flashback only the trap didn't have. And she/he suddenly have bloody corpse. Sooo perharps it isn't his head but other ppl head. so i assume it either his/her or emi

Nah confirmed its rei
Why?
Clue : the body is missing
The first that have body missing is rei. It either rei fake head (doll) or someone head. Since rin doesn't really cry and somewhat know the secret and didn't tell a word. And it must be rin take revenge or he just like kudoku. But it can also the crazy girl since she didn't confirm death yet.
Twins (mysterious) :
Rei : not confirmed
Rin : confirmed

Emi : confirmed
Katsuya & eiji : confirmed
Agnes : confirmed.

Also why i think it was rei because michika said there only five bodies when 6 ppl death (excluding crazy girl, michika, and vee)

"rei take revenge" cuz well he close to rin thats why he kill agnes first? Dunno :v