Wario Land 3: Part 57: The Grasslands (Blue Chest)

With the High Jump Boots, Wario can reach the high ledge at 0:43, where a ladder leads to a room that contains the Blue Key and Chest. He climbs the ladder, encounters red enemies that feed him apples to transform into Fat Wario, which he uses to clear Doughnut Blocks. Then he uses a Silky to become Ball o'String Wario and clears a large String Block. In the next room, he faces more Purple Blocks and enemies, and again uses Ball o'String Wario to clear another String Block to reach the Blue Chest. The Blue Key is located further up the ladders in a different room, requiring the help of a Stove and Bouncy Wario to reach it. The Grasslands' Blue Chest Treasure is a Fighter Mannequin, and something else fancy to keep!