TV-Series
Description
Duke Devlin, known as Ryuji Otogi in the original Japanese version, is a character who first appears following the Duelist Kingdom tournament. He is the creator of the game Dungeon Dice Monsters and the owner of the Black Clown, a game shop that serves as a rival to the Kame Game shop run by Yugi Muto's grandfather. Physically, Duke is a tall sixteen-year-old with a lean build, standing 179 centimeters tall. He has dark, spiky black hair, light brown skin, thick eyebrows, and dark gray eyes, often distinguished by the thick line makeup worn under his eyes.

Duke's background is defined by his encounter with Maximillion Pegasus. He invented Dungeon Dice Monsters and visited Pegasus to demonstrate the game shortly before the Duelist Kingdom tournament. Duke was impressed by Pegasus's skill, and Pegasus in turn enjoyed the game, approving its creation and intending to expand it further. At Pegasus's request, Duke allowed him to make additions, including the Dark Magician monster, and Pegasus also hacked into KaibaCorp's computer system to add some of the game's data. However, when Pegasus disappeared after being defeated by Yugi Muto in the Duelist Kingdom finals, Duke angrily blamed Yugi for his idol's disappearance. Convinced that Yugi must have cheated to beat a gamer as skilled as Pegasus, Duke swore to get his revenge on the one he believed did not deserve the title of King of Games.

When Duke transfers to Domino High School, which Yugi attends, he immediately becomes popular, impressing female students with his numerous dice tricks. This popularity breeds jealousy in Joey Wheeler, who confronts Duke and eventually challenges him to a game of Duel Monsters. The stakes are high: if Joey wins, Duke will close his shop; if Duke wins, Joey will become his slave for a week. The duel takes place at the Black Clown and is televised by Duke specifically to humiliate Joey. Although Joey initially takes the lead, Duke ultimately turns the tables and wins in a single turn, forcing Joey to become his servant and dress in a humiliating dog suit.

This treatment of his friend prompts Yami Yugi to challenge Duke. Duke, however, is not interested in a standard Duel Monsters match and instead challenges Yugi to a game of his own creation, Dungeon Dice Monsters, with the condition that if Yugi loses, he must swear on his grandfather's life to never play Duel Monsters again. Despite having never played before, Yugi struggles but manages to learn the game and ultimately wins by using the Dark Magician monster that Pegasus had added. Through this match, Duke realizes that Yugi plays honestly and would not have cheated against Pegasus. He begins to worry about the bad publicity his actions have generated, but Yugi and his friends comfort him, acknowledging that Dungeon Dice Monsters has great potential. Shortly after, Duke receives word from Industrial Illusions that they will help produce and distribute his game globally, allowing him to reconcile with the group and become their friend.

As a person, Duke is initially presented as arrogant, rude, and highly competitive, willing to cheat to achieve his revenge. He possesses a strong tenacity and an aesthetic focused on winning, though he also has the capacity to acknowledge opponents who prove themselves equal or superior to him. After his defeat and subsequent reconciliation, he becomes much more kind-hearted, friendly, and reliable, acting as a clever and witty supporter of the group. Despite his calm and confident demeanor, he tends to enjoy the attention of girls and develops a notable crush on Serenity Wheeler, Joey's younger sister.

Duke's role in the story evolves significantly after his initial antagonist turn. He remains a recurring supporting character, often acting as a commentator during duels alongside his friends. During the Battle City tournament, he becomes directly involved by saving Serenity Wheeler and Tristan Taylor from the Rare Hunters, meeting Mai Valentine in the process. His most prominent role comes during the Virtual World arc, where he, alongside Serenity and Tristan, duels Nezbitt of the Big Five. Confidently stating, You may not know me, but dice are my specialty, he proves instrumental in securing their victory. He later helps Joey when he collapses after his brutal duel with Yami Marik and cheers enthusiastically for Yugi during the Battle City finals. His friendships with the group solidify, and he develops a particularly comical dynamic with Tristan Taylor. The two become friendly rivals, often competing for Serenity's attention, which provides moments of levity without serious conflict. He also forms a supportive friendship with Joey, putting their initial animosity behind them.

In terms of abilities, Duke is a genius-level game designer, as evidenced by the creation of a complex game like Dungeon Dice Monsters. He possesses extraordinary dice-manipulation skills, able to perform impressive tricks and rolls that demonstrate his dexterity and understanding of probability. As a duelist, his strategies are similarly luck-based, relying on dice-rolling cards and monsters from his own Dungeon Dice Monsters game, including powerful creatures like Orgoth the Relentless. This reliance on chance and probability is a core aspect of his dueling style, mirroring his showmanship and gambling spirit.