Wanting to prove that man-made fighter units are a necessity and to prove his worth, Isamu and Yang (the YF-19's engineer) take the fighter jet and space-fold to Earth to beat the X-9 at its own game, while Guld gives chase in the YF-21. Sharon hacks into Earth's outer space defences, but both Isamu and Guld make it through. They then proceed to attack each other again, as they argue about childhood grudges. At the climax of the fight Guld, finally achieving a target lock, releases a large fury of missiles seemingly destroying the YF-19. As this happens, Guld is flooded by repressed memories. Now realizing it was truly his own jealous rage that had torn the friendship apart. Having saved himself and Yang by cutting engine throttle and gliding, the YF-19 then appears in the skies above Guld and the two old friends reconcile.