The origins of the Fireproof Secret Diary go back to the Pyromania update. On day one of the update, 7 items began to drop through the random drop system: The Goldfish, Pocket Lint, Cheese Wheel, Banana Peel, Barn Door Plank, Secret Diary and the Damaged Capacitor.

These items each were part of an ARG (Augmented Reality Game). This is a game in which certain items or codes can be put together to get a message/end result. Once all the clues were put together, a message "Monday" was read. The following monday of this code being revealed, the rest of the Pyromania update dropped.

Before most of the content of the Pyromania update dropped (before monday) these items served no purpose rather than being clues the ARG. However, after the update, these items changed forms. Every item except the Secret Diary and Damaged Capacitor was turned into ash. The Secret Diary was renamed the Fireproof Secret Diary and is the only item with use today. It is a reskin of the Spellbook Magazine. This is not the only reason for its expensiveness; it was also the rarest item to drop out of all the other 7 items.

There are 660 known instances of this item.