If you want to acquire it, you must some work. First, Go to the Switch Board at the end of the corridor on the 4th floor and move the fuse in the switchboard. (to center part.) ※ From the left of the switchboard, it is marked as "Light", "Power", "Security Alarm". Second, Come back to the library and operating the air conditioner then the item falls on the floor.
In the Original, it is used to take out a Key.
In the Remake, it is used to open the Library door. ( Unlatch the door. )