I'm not sure how some people got it so quickly.
I have to wait until Midnight... which I suppose is appropriate.
**IMPORTANT IF STARTING A NEW GAME**
1) At the title screen, press any button.
2) Start a new game and select any of the New Data slots.
3) Name entry should pop up. Delete the default "Miriam" and enter the secret code. The code is what a person who goes to this forum would call themselves (or PM me for the answer).
4) If it succeeds, a specific sound effect will play.
5) Continue to select the difficulty level.
6) The game will start with the unlocked item inside of your inventory.
Your file’s name can be changed afterwards during the game, but your in-game item can only be unlocked when starting a new game.