Unfortunately, since the perspective of the series is through the MC(does he have a name? I don't remember D0=), and he sees almost all ghosts as normal people, its really hard to discern whether or not the girl was a ghost. While she can talk, so did the ghost girl that was in the bathroom in chapter 8 or 9, and she also looked completely normal. I'm hinging that the shark teeth woman was actually a ghost. That's why she said she would "live" there, even though.
On side note, that is one sexy costume she's wearing. The suspenders + the thigh-highs in cow print attire is really doing it for me >=03.