Nova

Nova is one of the main protagonists in Kingdom Hearts Birth by Sleep and Kingdom Hearts Birth by Sleep Final Mix. She was a Keyblade wielder along with Ventus before Leah and Sora ever became one, and was apprenticed to both Master Xehanort and Master Eraqus. She is the second youngest of the four composed of Terra, Aqua and Ventus.

She met them when she was found unconscious and was injured badly, and had no memory of what happened to her before she came to Castle Oblivion. At first she was afraid of them