This article is from the Final-Fantasy and other Square Soft Games FAQ, by firstname.lastname@example.org (Nick Zitzmann) with numerous contributions by others.
If this was a real RPG, Aya would theoretically be able to shoot down
every door she came into contact with. Unfortunately, Parasite Eve is a
computer RPG, and so the player has to live by the computer's rules.
That means that Aya will have to find keys for just about every door in
Here's a list of the keys, and where to find them...
Backstage Key: Search the burnt body in the first save room.
Rehearse Key: After getting the previous key, go into one of the locked
rooms and read Melissa's diary to receive this key.
Zoo Key: Inside the first save room in Central Park; search a drawer for
Weapons Key: It's sitting on a table in the department's screening room.
It's used to open the weapons storage.
Locker Key: A dying policeman will hand this item over. It's used to
unlock a special locker inside the department's locker room.
Morgue Key: Inside the save room in the basement of the hospital; search
the drawers to find the key. (It's discarded when used.)
Blue Key Card: Search the burnt body inside the morgue. (It's discarded
Green Key Card: Rescue the nurse inside the familiar-looking operating
room. (It's discarded when used.)
Elevator Key: On the 13th floor of the hospital, look in the hospital
records to find this key. (It's discarded when used.)
Warehouse Key: It's found lying on the ground on one of the first scenes
inside the Warehouse.
Klamp Key: First, deactivate the security system in the museum. Then,
return to Klamp's office to obtain this.