Maiami City
Noboru Gongenzaka
Archetype: Superheavy Samurai
A student of the Gongenzaka Dojo and one of Yuya's best friends. He's an advocate of a method of Dueling he calls "Steadfast Dueling", which is taught by his family's dojo; basically the exact opposite of Action Dueling, it discourages unnecessary movement (and thus the use of Action Cards).
Gongenzaka uses a Superheavy Samurai deck with no Spell or Trap cards at all, and many of his monster effects can only be activated when he has no Spells or Traps in his Graveyard. Superheavy Samurai can also attack while in defense position, using their DEF points for damage calculation.
- Badass Back: In his duel against Ankokuji, he goes into the arena and gives him the back in order to show his dislike for him as well as to show his new black belt. And damn, he looked badass.
- The Big Guy: He is very definitely one of the bigger characters. His deck also runs a Stone Wall strategy.
- Dark Is Not Evil: He is taught Dark Synchro by Kiryu, a summoning method reserved for Dark Signers, and yet is firmly on the side of Good.
- Catchphrase:
- "Unforgivable, this is unforgivable, [person name]!"
- Also some variation of "I, the manly Gongenzaka..."
- Charles Atlas Superpower: As a result of his Steadfast Training, Gongenzaka is a very physically strong individual. He can endure attacks from Real Solid Vision monsters often without losing his balance, can stand still while holding very heavy boulders, do karate chops strong enough to destroy a Real Solid vision spike, and when he draws in his Draw Phase, he does with so much strength that he releases a strong force of wind. He is strong enough to punch a hole into a wall of concrete without injury.
- Childhood Friends: With Yuya and Yuzu.
- Pride: During the Synchro Dimension arc, Gongenzaka is so adamant about his Steadfast style of Dueling that he hardly makes a difference in his tag team Duels. Near the end of the arc, however, he overcomes it.
Strong Ishijima
Archetype: Barbarian
Strong Ishijima is the champion of the Pro League. Ishijima was due to Duel the current Champion, Yusho Sakaki, but Yusho never showed up, much to his fury. He loses to Yuya when Pendulum summoning is created.
- Barbarian Tribe: His deck's theme.
Shuzo Hiragi
Yuzu's father and the current owner of You Show Duel School.
- Amazingly Embarrassing Parents: Embarrasses Yuzu before her duel with Masumi, by picking a field to highlight her 'cuteness.'
- Boyfriend-Blocking Dad: Acts this way seeing Yuzu embracing Yuya. Gongenzaka even has to restrain him from ruining their moment.
- Doting Parent: He cares very much for his daughter.
- Eccentric Mentor: He's pretty odd, though well-meaning.
Yoko Sakaki
Archetype: Lightlord
Yuya's mother and former wife of Yusho Sakaki.
- Armor-Piercing Question: She asks one to Yuya during her Riding Duel against him, regarding his philosophy being able to influence those serving Leo Akaba in the Dimensional War.
- Good Parents: Is this to Yuya from the moment she found him.
Tatsuya Yamashiro, Ayu Ayukawa, and Futoshi Harada
The three children that go to You Show Duel School. The three of them accompany Yuya and Yuzu wherever they go and cheer them on. They're the representatives for You Show Duel School in the Junior division of the Maiami City Championship.
Tropes associated with these kids:
- Two Guys and a Girl: Tatsuya and Futoshi are the boys, and Ayu is the girl. Platonic, by the way.
- Audience Surrogate: Tatsuya, Futoshi and Ayu are the youngest students in You Show Duel School and need to be explained many things; like the difference between Levels and Ranks or the conditions of certain effects.
- The Big Guy: Among the three, it's Futoshi.
- Took a Level in Badass: By Part 5, they are shown to have become strong enough to be the Top 3 duelists in the most recent Maiami Championship.
The owner of Kame Game and Yuya's boss.
Reira Akaba
Archetype: C/C
Reiji's little sister, first introduced in the ARC League as Ayu's first opponent. Reira is quiet to the point of no emotion, but seems to be constantly scared of something. She uses a CC deck, which revolves around copying the opponent's cards, and specializes in multiple types of Special Summoning, like Reiji. As her brother is confident about Reira's skills and power, he makes her one of the Lancers.
- Badass Adorable: While she's normally a nervous kid, she's a very skilled duelist.
- Broken Bird: The card she used to nullify the effects of Ayu's cards on her side of the field show that she sees the world as a cold, grey place. Later revealed due to her environment where she grew up.
- Dark and Troubled Past: Reira isn't actually related to the Akabas, but a child from a country where a war has raged on for decades. She lost any sense of will and identity and learned to copy people perfectly to survive. She was adopted by Himika to be made into a duel soldier against Academia.
Nakajima
Nakajima works at Leo Corporation for Reiji. He appears to work directly under Reiji and his mother.
Tsukikage
Archetype: Ninja
Himika Akaba
The chairwoman of LDS, and Reiji's mother. Her job seems to consist of going around the world to claim other Duel Schools under the banner of LDS, creating a huge network which Leo Corporation controls.
Tropes associated with Himika Akaba:
- Ambiguously Evil: She's a bit corrupt, but neither her or Reiji seem to be outright evil, not to mention her humanizing features such as caring for those that work under her. Then it's revealed that they're planning to defend against an invasion from Leo Akaba, so her actions seem more justified considering the circumstances. And then we find out the reason why Reira is so messed up, putting her back to this
- Benevolent Boss: Though ruthless to other duel schools, she's shown to care about her employees.
- Big Bad Duumvirate: Though she and her son ultimately have good intentions, they are still the conflict creators in the earlier arcs before Acadamia rears its head.
- Corrupt Corporate Executive: She's ruthless to other duel schools, but actually subverted, in that she is aware of Reiji's plan and actively supports him in it.
- Education Mama: A dueling example towards Reira. She wants to make another prodigy out of him, like Reiji, but it's implied that all she got was traumatizing him until the point she's afraid of her and pushes herself to win in order to not enrage her. Eventually it's revealed that Reira isn't really her daughter, but an orphan that was rescued from a war-torn nation. She threw away her sense of self as a defense mechanism and can only emulate others, so if anything she's just trying to make her into another Reiji.
Seto Kaiba
Archetype: Blue-Eyes
The head of the gaming company "Kaiba Corporation".
LDS Students
Hokuto Shijima
Archetype: Sacred
Hokuto Shijima is the representative for the Leo Duel School Xyz Summon course. Despite being a very arrogant jerkass, he has a great deal of respect for Xyz Summoning.
Masumi Kotsu
Archetype: Gem-Knight
Masumi Kotsu is the representative for the Leo Duel School Fusion Summon course.
Yaiba Todo
Archetype: X-Saber
Yaiba Todo is the representative for the Leo Duel School Synchro Summon course.
- Adaptational Nice Guy: Compared to canon, he shows upmost respect during his duel against Rin.
- Graceful Loser: When Rin displays an unimaginable comeback, he accepts his inevitable defeat with a smile.
Junior Youth Battle City Qualifiers
Michio Mokota
Archetype: Cookmate
Michio Mokota is a student from Kirigakure Cooking School, who is arranged to duel Ruri by Nico Smiley.
Eita Kyuando
Archetype: Quiz
Mieru Hochun
Archetype: Prediction Princess
Maiami Championship Participants
Ryota Kajiki
Archetype: Water
Amelda
Archetype: Army
Gen Ankokuji
Archetype: Barbarian
Gen Ankokuji is a participant in the Junior Youth Class of the Maiami Championship. He bullied Yuya and his friends when they were younger. He was a former member of the Gongenzaka Dojo.
Like Ishijima, he uses a Barbarian deck.
Valon
Archetype: Armor
Dinosaur Ryuzaki
Archetype: Dinosaur
Dinosaur Ryuzaki is the number 2 Duelist in Japan. He faces Sawatari in the Maiami Championship.
Isao Kachidoki
Archetype: Star
Isao Kachidoki is a participant in the Maiami Championship and is the Ace of the Ryozanpaku School. He is a martial artist with a very violent manner of dueling. Kachidoki was the runner-up of the last year's Junior Youth Championship. He is the second duelist Yuya faces in this year's tournament. He uses a Star deck and he is a Fusion user.
Mai Kujaku
Archetype: Harpie
Mai Kujaku is a participant in the Maiami Championship. She faces Ruri in the second round.
Ghouls
Marik Ishtar
Archetype: Egyptian God
Insector Haga
Archetype: Super Insect
Insector Haga is a member of the Ghouls.
Rare Hunters
Rishido
Archetype: Mythical Traps
Rishido is the second-in-command of the Ghouls, and leader of the Rare Hunters combat unit.
Seeker
Archetype: Exodia
Pandora
Archetype: Magician
