The seven school mysteries play an important role in this game.

The seven school mysteries are seven mysterious legends or ghost stories associated with a particular school. They typically appear in a Japanese school setting and vary from school to school. Some of the most common and well known mysteries include Hanako of the toilet, Aka Manto (Red Paper, Blue Paper), Teke Teke, the staircase with more steps coming down than going up or the number of steps changing at night (The 13th step), the living anatomical model or Blue-eyed Doll, the haunted music room (the piano that plays by itself, the shining eye on the portrait of Beethoven), the ball bouncing in an empty gymnasium, the pool haunted by the spirit of the drowned student, the statue of Ninomiya Kinjirō running laps around the schoolyard in the dead of night and the existence of the hidden 8th mystery. It is said that if someone learns all seven mysteries something wondrous or ominous will happen to them.

NOTE: A visual novel with this tag doesn't have to contain all seven mysteries.