A Zentradi/human hybrid, Guld grew up with his two friends Myung and Isamu on the rural planet of Eden. He shared a fascination for flying with Isamu, and the two managed to build a man powered flying machine together. Another thing he shared with Isamu was his love for Myung.

Years later, he became an employee for General Galaxy, both as a designer of variable fighters and a test pilot. His pet project, the controversial mind controlled YF-21, became General Galaxy's entry in the Project Super Nova competition. Much to his distaste his rival, the test pilot for Shinsei Industries' YF-19, is none other than his old rival Isamu. The competition between the two, flamed by their old rivalries becomes a bitter one. Things get even more complicated when Myung shows up in Eden as well, now the producer for the popular AI singer Sharon Apple who is on tour. In an early test flight of the YF-21, Guld fantasizes about forcing Isamu's VF-11 Thunderbolt to crash (having been rescued from a certainly fatal crash by Isamu's quick thinking himself moments earlier). The YF-21's control system interprets this as a command and pushes down hard on Isamu's fighter, forcing it to crash, which Isamu survives with only superficial injuries. Guld, determined to win, even manages to sabotage one of the tests in his favour by swapping live ammunition into Isamu's gun pod, which he later uses to fire into the YF-19 and nearly kills Isamu (he had been originally intending for the ammunition to be used by Isamu against him, to make it look as though Isamu had plotted to murder him). Just as Guld is starting to patch things up between him and Myung, she leaves for Earth to attend the anniversary of the end of the Space War. Meanwhile, Project Super Nova is cancelled when U.N. Spacy announce that they will go for the A.I. controlled X-9 Ghost. While Guld is mulling this, Isamu steals the YF-19 to stop the Ghost's inauguration on Earth. Guld is then tasked to bring him back using the YF-21. He succeeds in tracking down his rival and an intense dogfight ensues. During the duel, Guld accuses Isamu of stealing Myung from him, of ruining everything. Just as Guld landed a mortal shot on Isamu, all the suppressed memories flood back in, and Guld realizes his mistake.

One day Guld walked in on Isamu and Myung sharing a tender moment. His Zentradi warlike tendencies explode with jealous rage and he attacks his two former friends. As a result, Guld knocks out Isamu and attacks Myung. The trio broke up, Myung and Isamu leaving Eden. Alone on Eden, Guld's psyche managed to suppress the memories of his assault, convincing him that he was protecting Myung from Isamu's unwanted advances. Luckily for the grieving Guld, Isamu managed to escape in the last moment. But just as they start to bond again, the X-9 Ghost appears, now controlled by the crazed Sharon Apple and attacks the two. Guld manages to convince Isamu to leave this fight to him, and go rescue Myung instead. The fight goes in the Ghost's favour in the beginning, as Guld can barely keep up with the Ghost's aerobatics. In one last act of sacrifice, Guld removes all the inhibitors from the YF-21, allowing him to execute dangerously high-G maneuvers. He reconciles himself with both Isamu and Myung over the radio and destroys the X-9 Ghost, killing himself in the process.
(Source: Wikipedia)