Princess Vanilla is an unused character from Harvest Moon 64. Not a lot is known about her besides her sprite and some translated dialog.
According to the dialog her story goes as follows:
Princess Vanilla was turned into a turtle, kidnapped from Prune Kingdom in Flower Country by a mole, and was going to be forced to marry a frog. The player finds the princess after she had been talking to some Harvest Sprites. If he chooses to pick her up, he will become a turtle as well. After this, he can wonder around and talk to the villagers so they can react to him. Eventually, possibly from Karen's kiss, he returns to normal, and proceeds to turn the princess back as well. From then on, Princess Vanilla stays in Flowerbud as a regular character.
After this, there's some dialog between her and other characters. She asks the player if she or a specific other girl is prettier and becomes upset if she is not chosen.It is unknown what else may have been in store for this character or why she was excluded from the game.