Just because you were mentioned as guarded doesn't mean you couldn't kill. The description doesn't mention names, nor does it ever say "X character did nothing". Nothing in the description indicates that you couldn't have done it.
Since we've established that the killer is a girl and the other girl watched didn't do anything that night, the answer is clear as day.
##Vote: FFNut
That means:
FFNut - 3/4 (Formalhaut, Scruffington, Fynn)
Aerith's Knight - 1/4 (FFNut)
No Death (1/4) (Fox)
I honestly don't think it could be anyone else at this point. I feel kind of stupid that I fell for his line of thinking last round, tbh.