Strider Hiryu was the youngest Strider to ever reach the rank of "Super-A" grade. He was the greatest Strider the organization has ever produced, but he eventually grew disenchanted with them and retired. An uncollected prologue tells how Hiryu had been forced to kill his sister, Maria, who had inexplicably gone insane. He left the Striders for Mongolia, where he lived in seclusion for some years.
The collected manga opens with a Strider assignment gone horribly awry. Two Striders, Kain and Sheena, had been assigned to Kazakh, but were ambushed by a paramilitary organization. Kain and Sheena defended the city valiantly, but were eventually overcome by the simplest of ruses: an armed child. Sheena managed to escape, but Kain was captured by a military officer bearing the Strider tattoo.