Young Kai has passionately idolized Ginta ever since the hero's battle in the War Games six years ago. Since that time, ARMs have become commonplace, especially Guardians! Kai himself does not possess one, however, and dreams of obtaining an ARM like Ginta's. When his caretaker, the elderly ARM-smith who took him in after his parents died, sends him on an errand, he is attacked by a bandit from "chess". During his attempt to escape, he finds more than he bargained for upon encountering Babbo. But now, with Babbo's awakening, the fake ARMs are going out of control! Is it Kai's turn to save MAR Heaven, following in his hero's footsteps?