New Game Plus...
	New Game+...

Once you clear the game. Go to the Phantom Island, and speak to the black spirit. Pick the first choice.

You get these characters for New Game+ by Beating "Another Marona". You keep your characters you started with and also unlock Carona.

Character	How to unlock
Carona	Beat Another Marona.
Raphael	Beat Another Marona.
Sprout	Beat Another Marona.
Walnut	Beat Another Marona.