Quo Gray is the secondary antagonist of the mang Mobile Suit Crossbone Gundam Ghost. He is the leader of the mercenary group Thoucus, and was a student of Karas. He is interested in the possible value of the alien bacteria Angel's Call, and desired to obtain and sold it as bio-weapon for the profit. In order to achieve this , he worked with Kizo Dogatie.
Quo is a typical greedy businessman, willing to do everything to obtain a high profit, which includes selling the dangerous Angel’s Call, ignoring the possible disaster caused by it. He also has no problem in betraying people, as he betrayed Kizo once he located the Angel's Call. He is very proud of the Thoucus, gladly having his minions to combat the Zanscare Force abandoned by Kizo in order to show the latter of them being worthy to be hired to fight Serpiente Tacon. Despite this, he cared about his subordinates, screaming to tell Kosher to escape from being killed by Kizo.
Coming from the Jupiter Empire, Quo Gray was educated by Karas, thus, Quo too believed in that stronger shall overcome the weak. At some point, Quo became the leader of the mercenary group Thoucus, which was originally a unit of the Jupiter Republic that focus on developing Mobile Suit that can combat thousands of enemies at once, The group is mainly consisted of criminals with death penalty, who wears mask in battle in order to hide their identity.
At some point, Quo would have a meeting with a captain from the Zanscare Empire. In the ship, the captain objected to Kizo about working with the Thoucus, since they wiped out their force earlier. And Quo asked Kizo to hire them, since with that, the Thoucus's Mobile Suits that are capable of destroying one thousand enemies would finally be in action. At first, Kizo didn’t trust Quo, but since they were suddenly attacked by Serpiente Tacon. Quo decided to use this chance to prove themselves worthy to be hired. Quo then sent his minions to combat the incoming enemies and the Zanscare captain's force. In the end, the Serpiente Tacon barely escaped, while the Zanscare captain and his force were all easily killed by the Thoucus. Satisfied, Kizo hired the mercenary group.
Quo Gray soon received his first mission, to enter Font's home colony "Cartoon Meat" and kidnap children to threaten Font's parents to surrounded or else Quo would have them executed under Kizo's order. Font was lured in, and was easily captured, Kizo and Quo then revealed that this is all just a trap to force him to reveal the location of Angel's Call. Quo admitted that he was impressed by Ki zo's trap. After Kizo revealed that he would have the captured children beheaded, Jack Friday, a member of Thoucus angrily beat up Font for not listening to Kizo since he doesn’t want the children to be killed, forcing Quo to clam him down.
Soon, Font and the children together with Belle escaped from Thoucus's ship, however , they were soon captured again by Quo and Gordon. Just before Quo was able to have a kid executed, Font was able to fully activate the Phantom Gundam and used it to easily defeat Jack and Gordon, much to the disbelief of Quo. Soon, the Serpiente Tacon also arrived, resulting in the defeat of Quo. Despite this, Kizo was still willing to hire them.
Soon, the location of Angel's Call was finally revealed, and despite of his alliance with Kizo, Quo sent Animar, Diva and Mermaid to combat Serpiente Tacon and Zanscare force. Kizo was aware of this, which Quo explained as its normal of businessman to have multiple clients, Quo and the Thoucus then went to Maria City. Soon, when Kizo was ready to retreat from the city, Quo contracted him, which Kizo replied that he was aware that Quo would betray him. Quo then answered that it was because if the Angel's Call was obtained and sold as a bioweapon, they would earn a large sum of profit. Quo then cut their talk and went on with their next plan.
In space, Kizo and Maria El Tomoe were ready to battle the Serpiente Tacon for the last time, however, before Kizo was able to get into the cockpit of Midas, his force were attacked by Quo, who was piloting the Grego Mobile Suit: A Mobile Suit with almost every Thoucus Mobile Suit's specificities combined together. Kizo was then ready to combat Quo. However, Quo suddenly opened the cockpit of Grego, Kizo then fired a bullet with Angel's Call in it to Quo, sInce Quo espected this, he wore bullet-prove armor and successfully obtained the Angel's Call. Quo and Kizo then combatted, as they were interested in each other's Mobile Suit. At first, Quo seems to have the upper hand, and was even able to grab Kizo and his Midas with Grego's giant arm. Kizo pretended to ask for mercy. After Quo rejected him and was ready to deliver the killng blow. Kizo activated the Midas Torch Force, deactivating the Grego and many other Mobile Suits. Unable to fight anymore, Quo begged for mercy, only for Kizo to reject him and fired a projectile with Angel's Call into the Grego in order to finish Quo off. To Kizo's surprise, Quo survived, and opened the cockpit to fire his bazooka at the Midas just as Kizo sliced Quo and his Grego in half, killing him. Despite of Quo's death, he was able to damage the Midas's sensor with the bazooka, which cause Kizo to be no longer able to use Midas Torch Force anymore .