Fifteen children at a summer school program encounter the mysterious Kokopelli and agree to be testers for a game he claims to have completed recently. Soon, they are summoned into the cockpit of a giant mecha, with Kokopelli piloting. Thus the first round takes place.

Jun declines Seki's offer and becomes the pilot for the final round. During the long battle, he reminisces about his fallen comrades while struggling to save the Earth once and for all.