The Black Keys are key items in Paper Mario: The Thousand-Year Door.
The black keys are simply put as basic black-colored keys that are used to open the large black chests Mario comes across on his quest. There are four Black Keys that appear in total. Each one opens a respective Black Chest found within the same chapter and area as the key. The Black Chest opened by these keys contain a Black Chest Demon, which, upon the opening of the chest, "curses" the opener. When Mario opens one, he masters a new paper-based ability on foot. The Black Keys should be easy to find since they are usually close to a Black Chest.
Black Key Locations
- Rogueport Sewers: The first Black Key in the game can be found on a ledge below the Black Chest.
- Hooktail Castle: The second Black Key in the game can be found in the infamous spike room of Hooktail Castle. After opening a treasure chest containing the Black Key, Mario must quickly escape from the room or he will be crushed by the spiked ceiling.
- Twilight Trail: The third Black Key in the game can be found in a shed at the beginning of Twilight Trail.
- Pirate's Grotto: The fourth and final Black Key in the game can be found in an old ship of the Pirate's Grotto. Mario must defeat an Ember in order to make the Black Key appear and the Black Chest is in the same room as it.