Heaven or Hell Achievement
Heaven or Hell50
Read the manager's notebook in the observation room.
After finishing the fifth floor puzzle, you'll go back to your room on the first floor and sleep, like you did after every floor. Upon waking up, when you leave your room and turn right toward the elevator, you'll see the door on the right next to yours is open. Go inside and to the table and press to look at the notebook on the table. This will unlock the achievement.