Lulu (stereotypically called the Mysterious Girl) is a self-proclaimed Luxeville's hero and Wario's arch-enemy in WarioWare Gold. Her name is revealed in Wario's final stage (Wario Deluxe) in WarioWare Gold when she introduces herself after his defeat.
Lulu told Wario that she will get him and he teased her. After completing Mona's microgame set, in Crystal Park, Lulu hazed Wario and shot water with the watergun at the target. As a result, Lulu was amused with the rainbow appearing. After completing Dr. Crygor's microgame set, she eats food until a small dog, Ruffington approaches her. She lets him eat and they sleep during the day after finishing the food. After completing 9-Volt's microgame set, Lulu wakes up and realizes that Wario is getting away and thanked the dog for the snuggles.
Wario as Wario Deluxe after his corruption encourages the player to give up, until Lulu refuses and helps the player by distracting Wario which the controls scheme hints returned. After the Boss Stage is defeated, Lulu introduces herself and demands him to give the pot; but Wario refuses. Lulu had one option to squirt him with her Hydrocannon LX. The pot fell off his head and she told him that it was a potty. Wario was amused and let her return the potty.
Lulu and Ruffington returned to Luxeville with the potty. The elder tells Lulu that they recently installed a modern toilet which Lulu faints.
Lulu can also be used for the game mode, Wario Interrupts. She helps the player remove obstacles in the way.