Favorite of the Firbits. Can smell it a mile away.”— In-game description
The Grape Juice is a key-item that is found in Dark Cloud 2.
This item is given to Max by Conda when he's first encountered in the Firbits' House in Sindain. As Max and Monica ask for help about restoring Sindain, the tribe's chief, explains to them that him and the tribe does not have any news of Holly. Conda then asks the two to search for Holly and for the team which was formed to retrieve her.
In order to have less trouble finding the firbit's team, Conda gives to them a bottle Grape Juice, since it's the favorite juice of the Firbits, as they can smell it from very far.