I'm not incredibly interested in seeing any more of this particular ghost, or having Reiko interact with any other ghosts. Of course, if that's what the author wants to do, fine, and maybe it'll be good.
But to me that path just inevitably leads to gratuitous world-building, and the generation of a bunch of technical questions about how ghosts work in this storyworld, etc.
Some backstory on Reiko herself would be welcome, but I'm mostly here for the cute, not for a Mieruko-chan knockoff.