The Red Key is a guaranteed reward from defeating the Dough King, provided you deal at least 10% of the boss's total damage during the fight. This requirement encourages active participation rather than simply being present for the kill.

Usage:

The Red Key is used to unlock the door leading to the Cake Scientist. Once unlocked, the Cake Scientist allows players to purchase a Dough Raid Microchip for 1,000 Fragments or by trading a Blox Fruit with a value of $1,000,000 or more. The door only needs to be unlocked once, allowing permanent access to the NPC afterward.