Well, from what I know, it could be about the girls in the 'To Love - ru Darkness' universe encountering strange apparitions. Maybe there are some haunted places they come across and they have to deal with the supernatural in their own unique ways. Since the original series has a lot of comical and romantic elements, perhaps this 'ghost story' version adds a spooky twist to those aspects.
I'm not entirely sure as I haven't read it in great detail, but generally it might involve the characters from 'To Love - ru Darkness' getting involved in some spooky and mysterious events related to ghosts.
The 'To Love - ru Darkness Ghost Story' might center around the daily lives of the characters being disrupted by ghost - related incidents. It could be that the male lead, Rito, and the various female characters find themselves in situations where they need to figure out the mystery behind the ghosts. This could lead to some interesting character development as they face their fears and try to solve the spooky problems, all while still maintaining the charm and humor that the 'To Love - ru' series is known for.