Yu-Gi-Oh! GX Manga Only Characters

Ryuga
Ryuga (龍牙, Ryūga) is a teacher trainee assigned to duel fifty students in Duel Academy. On the condition that he could pass them all, he would be recognized as an official professor of the school. He is rumored to take the cards of those he defeats. When he duels, he uses a special ring to emit an electromagnetic force that disables his opponent's Duel Disk, preventing their use of Spell Cards. He challenges Jaden, but the duelist defeats Ryuga with his Trap Alternate Fusion card.

Ryuga uses a Dinosaur Deck, which utilizes the brute force of monsters such as Cyber Dinosaur to defeat his opponents.

Seika Kohinata
Seika Kohinata is a manga-only Obelisk Blue student and Miss Duel Academy for the past two years. However, she discovers that Alexis has the same number of votes. When it's revealed that Jaden has the deciding vote and also happens to be Alexis's friend, Seika suspects that it was a ploy by Alexis in order to win, even though neither Alexis or Jaden has any interest in the competition. Seika challenges Jaden to a duel for his vote, but Alexis decides she'll take Seika's place. If Jaden wins his vote will go to Seika while if Alexis wins, she's allowed to drop out of the competition, making it a win-win situation for Seika. Even though Jaden wins in the end, Seika decides that Alexis should be Miss Duel Academy as she has proved to be better qualified.

Seika later appears to duel Jaden in the finals of the tournament. She uses a Snake Deck.

Kouyou Hibiki
Kouyou Hibiki (響紅葉, Hibiki Kōyō) is the younger brother of Midori Hibiki and once a three-time Duel Monsters champion. Kouyou was a great pro-league duelist who used E-Heroes. Chazz received an autograph from him, and in the process, Kouyou's Winged Kuriboh altered Chazz's Light and Darkness Dragon card. However after a battle with a mysterious duelist, his health began to decreased. He was sent to the hospital where he met a young Jaden who had broken his leg while playing baseball. He taught Jaden all he knew about dueling and to always have fun dueling no matter what. With his health failing, he decided to give up pro-dueling and made Jaden his final opponent. After defeating Jaden, he gave him his deck and his lucky red jacket. He eventually falls into a coma.

Kouyou's full name means "autumn colors".

Kouyou plays an nature-based Elemental Hero Deck. Before the start of the manga, Kouyou gave Jaden his deck, including the one-of-a-kind Elemental Hero Terra Firma card.

Midori Hibiki
Midori Hibiki (響みどり, Hibiki Midori) is the headmaster of first-year Slifer Red students at Duel Academy. She is a kind person who actually bought Jaden his first Duel Disk. Though her deck is unknown, she is one of the few duelists that her brother, Kouyou could never beat even when he went pro.

David Rabb
David Rabb is a duelist from the United States and companion of Zane who he follows to Duel Academy. After arriving at Duel Academy along with Zane and Reggie, David participates in the tournament hosted by Duel Academy, easily trouncing Syrus. He later crosses paths with Jaden Yuki, but decides not to duel him because of his Slifer Red status as the defeat of a Slifer Red will get him a meager amount of points compared to Ra Yellow and Obelisk Blue students. David is fluent in both English and Japanese as he is able to easily communicate with a culture-shocked Jaden who assumed he couldn't speak in his native tongue.

Deck:
 * The big SATURN

Reggie MacKenzie is a fictional character exclusive to the Yu-Gi-Oh! GX manga. Like David Rabb, she is an American duelist and accompanies him and Zane Truesdale to Duel Academy.

Character biography
After arriving at Duel Academy with David and Zane, Reggie participates in the on-going tournament hosted by Duel Academy. Her first major opponent is Alexis Rhodes whom she near-effortlessly defeats. She later questions Alexis about Jaden Yuki, seeming to be interested in his ability to see Duel Spirits.