Combine soy sauce, ginger, garlic, sugar and water. Marinate meat in the mixture in a plastic bag overnight in the refrigerator.
Preheat the grill to high heat. Skewer meat on skewers. Cook over hot coals until done to your liking, about 4 to 5 minutes for medium rare.
Place pineapple slices on grill. Cook on both sides until there are grill marks and the natural sugars have helped it to brown, about 2 minutes per side.
Place beef skewers on top of grilled pineapple slices and garnish with mint.