Masterless CP, fake harem, two men and two women both love and hate, so that's fair
The heroine has no intentions towards anyone
If the ghost's obsession is too deep, it will be trapped in the place where its obsession is. Ghosts that are not that deep can open up a new area of activity (but they must choose an object here to possess as a medium, but it will be weaker than where they died or where the obsession is), but they can still go outside the area. To cause trouble (the strength will be greatly weakened), enter the area and kill the ghost to come out (for those who are too obsessed, the ghost can choose to run away by itself if the spirit is possessed). If you don't kill, you will be killed, and you can't get out even if you hide. Of course, if the ghost is timid, you can just beat the ghost away and leave.
(The main idea is to play a dungeon, but also want to create some scenes of chasing ghosts and then blah blah blah... That's it!)
Concept: What is a ghost? Is it tasty?