Hyū (ヒュー), is the head of the three Zymot Usurpers and the main antagonist of series 1 and a major antagonist of series 2. He wears a mask over his mouth until Amil Gaoul (the Key Spirit he stole from Zed ) rejects him. He has a strict personality, but acts somewhat insane after he's rejected by Amil Gaoul. He is the previous owner of the Key Spirit, Pronimo, later stolen by Sara after Hugh's defeat.
Hugh's first appearance was in episode 7, in which he's shown next to his two primary officers, Glaudio and Elmelda. He used Dumas as a spy, manipulating Dumas in believing he will become the next king of Zymot by marrying Rebecca.
At an earlier age, Hugh acted as the primary retainer under Rebecca's father, who was the king of Zymot at the time. One day, however, Hugh had attempted to kill him, which was when the king placed his half key Spirit into Rebecca's forehead. Due to this fact, Hugh continuously captured Rebecca and later convinced Rebecca's father, whom he had let live, that he would marry Rebecca and become the new king of Zymot. This is only a trick, however, in order to make Rebecca's father release the shard within her head. After Hugh receives the shard, he kills Rebecca's father and casts her away, free to do whatever she wishes. After this event, Hugh became the new King of Zymot, and lusts to obtain every key Spirit he can get his hands on; this is Hugh's true ambition.
Hugh then furthers his influence by gaining the trust of many major figures within Tusk . After Hugh's campaign in the Kalbu-fu region, he meets up with Zed and finally realizes that he has Amil Gaoul in his possession. Hugh flees after he realizes that his key Spirit Pronimo (becomes whole after fusing with the fire half) cannot stand against Amil Gaoul. After Roya was to be sacrificed at a different time by the creatures of Tusk, Hugh takes glimpse of Noa's key Spirit along with Zed's, which makes his ambition burn even stronger. Hugh later retreats and continues to elaborate on his superiority within the series.
Hugh later participated in the Neotopian Joust, disguised as a representative of Tusk. After Zed was 'defeated' by Noa and taken to a hospital to recover, Hugh crept into his room at night and stole Amil Gaoul. The next day, Hugh, still in disguise, faced off against Noa in the final match of the Joust. During the battle, Noa knocked off Hugh's helmet revealing his true identity. At this point, Hugh summoned Pronimo to battle against Sachira, but then summoned Amil Gaoul to double-team Noa. Just when it seemed that Noa was defeated, Hugh was overcome with intense pain and regurgitated Amil Gaoul's shard. Noa, mentioned that Amil Gaoul had rejected Hugh, and the pain he was feeling was his punishment. Before he could be captured, Hugh teleported away, back to Zymot.
After returning to Zymot, Hugh stopped wearing his mask and revealed his true face, a menacing, devilish visage. It seems that the after-effects of having Amil Gaoul have also twisted Hugh, making him slightly insane. He has recently begun an invasion of Neotopia along with an army of Tusk beastmen.
Zed hits Hugh with a shard explosive and then stabs him through the torso. Pronimo and Amil Gaoul return to their owners as Hugh drops dead, revealing a face clothed once again.