The Mystery Girl is a Creator from the Universe of Sound, her mission is to track down Boom and find out what the radio has discovered about the Ghost. X-Boom, an ASD with a quantum CPU, is her partner in the complex mission. For almost all the first season she's the real antagonist of the Ghost and manages to stop him thanks to the musical calligraphy and its sonic suit, which allows she's not to be tracked through the Space-Time folds. She comes into contact with the company of friends and explains the beauty of the Universe of Sound. In addiction she helps first Stella and Marco and then Pepi and Felix to find their way around the Boundary between the two worlds.