Yogurt Guard is the name given to a sidequest in Baten Kaitos: Eternal Wings and the Lost Ocean. The quest consists of providing a guard in Corellia's Palace with Pow Milk Yogurt before traversing the Celestial Alps. You're rewarded with Sagitta immediately and later Fairy Barrette (after traversing the Alps). Later in the game you can find the guard standing next to the door on the left at the bottom floor.