A frequent recurring character, driving car number nine (the “Shooting Star"), is the enigmatic Racer X , a flamboyant, mysterious and often brooding soldier of fortune whose secret identity is that of Rex Racer (Ken’ichi Mifune) Speed’s older brother, who years earlier had a falling out with the family and exiled himself. Rex left home estranged from his family and assumed the Racer X identity to pursue his racing career after arguing with Pops about it. He stayed in the background looking out for Speed, often rescuing or assisting him. Racer X always left the scene unnoticed, receding into his secret life. The “M” on his tunic stands for Mifune, the family name.