It was implied in chapter 3 that Ako had previously atttempted suicide. The near death experience caused her spirit to become unstuck, making her a semi-ghost when she sleeps.
@ValKnight Same. I checked it out on a whim, since it's not my usual fare, but I'm finding it oddly appealing. The pacing really is good, with the way the author gradually drops hints in.
So there is gonna be some drama/romance between him and the ghost now I guess?
It looks like almost all the pieces have been set at least, can't wait for the next chapters.