- Research Hall, on a corpse near the "Patient Room Floor 3".
Unlocks all of the cells in the Dungeon, with exception of the one that lies beneath.
- This item allows access to the Yamamura Set and the Church Pick. It also allows players to summon Yamamura later on if they equip the Impurity rune.
- Players can jump from atop the ladder that can be climbed, from the "Patient Room Floor 2", to reach the key without having to climb to the top of the Research Hall. This allows earlier access to the above mentioned gear.
- One of the two keys that unlock cells in the dungeon, the other is the Underground Cell Inner Chamber Key.
- Like the Balcony Key, this too is a very stubby key, the only other one like it.