Supernatural Note

Ten years ago, a student fell from the toilet window of the school and died late at night. Then, the building began to stage "campus incredible events" one after another. Women wandering alone in the corridor at night, crying from the toilet cubicles... All this has gradually become dusty with the abandonment of the building.
Ten years later, at the request of the mysterious client, the supernatural research society came to this teaching building again. What happened that year? After ten years of exploration, can we find the final truth?