Unlike the sequels that follows you take on the role of Kenta, a high school student trapped by Isaku, the eldest brother of the Itou Family on the last floor of an abandoned school building together with fellow classmates and a teacher.

The main objective of the game is to have the player and his companions escape from a locked school building, and to avoid having your companions captured by Isaku.

The only way out is through a stairwell, the doors of which are locked on every floor. The player must search the rooms on each floor for clues and items that will lead him to locate the keys that will open the stairwell doors and allow him to descend to the next level and ultimately to a final confrontation with Isaku himself.