Lullaby Princess has grayish skin and short, black hair that is shaped like a music note. She wears a black and white dress that is designed to look like a piano, as well as a gold sash. She also wears a gold crown with a green gemstone embedded into it.
Lullaby Princess is one of the three canidate princesses to rule the Nameless Kingdom. However she and her sisters (the other two princesses) mysteriously disappear, causing Pillowmint Butler to send Finn and Jake to retrieve them so a ruler can be chosen. At the end of the game, Finn chooses one of them to be the ruler of the kingdom. If Lullaby Princess is chosen, a song is played at the end of the game.