A young stranger, whom appears to be an Alien Gold has been sighted wandering around a park by two schoolgirls, with one of them was rescued by him from several bullies sometime ago. The alien was tormented by several youngsters and tries to activate Rudian, provoking Xio to take action. Daichi realises that Alien Gold has no malicious intent, having healed a schoolgirl earlier. The alien tries to search for hislost ship but accidentally faints when piloting, causing Rudian to wreak havoc in the city. Ultraman X and Sky Musketty put a stop on it and the Alien Gold manages to regain consciousness to deactivate the robot before fainting again. While Alien Gold is under custody, Chief Minamikawa from UNVER Japan Branch wants the alien dead, believing him as a threat. Alien Gold awakens and reveal what happened: back in his past, his home planet was under attacked by Gargorgon, a similar monster that destroyed a civilization in the human history. That monster will arrive on Earth for the Planet Gold energy in Rudian and he must use the robot to stop him. Soon Gargorgon appears and Minamikawa orders Gold to be surrendered but halted by Captain Kamiki. Knowing Daichi's relation to Ultraman X, Gold seek their help and the two agree, as both Ultra and robot face the arrival of Gargorgon. Before the battle, Alien Gold introduces his name as tE-rU and thanks Daichi and X for their support.