Chô shôjo Reiko (1991)

The school's annual festival is mere weeks away and students should be focused on that and their studies, but instead paranormal occurrences are happening and nothing is what it should be. A group of intrepid students form a squad to investigate the phenomena, and are aided by Reiko who possesses supernatural powers. Soon it becomes a battle of wills between Reiko and the ghost of a former student.