"after being possessed by the Frog Devil, Kirby now known as Froggy went on to destroy the entire town as well as take DeDeDe's castle with it. he now rules over pop star, anyone who comes into the range of Froogy often ending up looking like Swiss cheese. They are called Froggy or The Frog Devil. Froggy has come here to cause as much violence as possible because it fills them with glee.their intentions? kill on sight" Extra LORE!!!: How the gun ended up as his arm is because froggy used the copy ability but it didn't work fully. So the gun is his arm
