In the anime, Duke invented Dungeon Dice Monsters and visited Maximillion Pegasus to demonstrate the game shortly before the Duelist Kingdom tournament. Duke was impressed by Pegasus' skill at the game. Pegasus himself enjoyed the game and approved of the creation of Dungeon Dice Monsters, wanting to expand it further. Upon Pegasus' request, Duke allowed him to make additions to the game, like the "Dark Magician" as a monster and also hacked into KaibaCorp's computer system. However, after Pegasus disappeared after being defeated by Yugi Muto in the Duelist Kingdom tournament, Duke blamed Yugi for his disappearance and believed that Yugi must have cheated to beat a gamer as good as Pegasus. He swore to get revenge on Yugi whom he believed didn't deserve the title "King of Games".
After the Duelist Kingdom tournament, Duke opened the Black Clown (a rival game shop to the Kame Game) and was transferred to Domino High School, the school that Yugi attends. He quickly became popular and impressed girls with a number of dice tricks. Joey Wheeler became jealous and challenged Duke to a game of Duel Monsters. They agreed to the stakes which were that if Joey won, Duke would close his shop and if Duke won, Joey would be his slave for a week. Having been the runner-up in Duelist Kingdom, Joey was certain that he would win. However, not having his own Deck, Duke insisted that they play using cards straight from Booster Packs. Joey agreed and they each created a Deck.
The Duel takes place at the Black Clown. Duke televised the event in the hopes of humiliating Joey. Over the first few turns Joey knocked chunks out of Duke's Life Points while leaving his own unscathed, but Duke managed to turn the Duel around and take out all of Joey's Life Points in one turn.
In keeping his end of the bargain Joey became Duke's slave. Duke further embarrassed him by having him dress in a dog suit. Yami Yugi was disgusted by his treatment of Joey and challenged Duke to a Duel to release Joey. Duke was not interested in Dueling and challenged Yugi to a game of Dungeon Dice Monsters. If Yugi won, Joey would be free again, but if Duke won, Yugi was to swear on his grandfather's life to never play Duel Monsters again.
Duke also televises his game with Yugi. Having not played Dungeon Dice Monsters before, Yugi struggles at first and Duke gains an early advantage. However, Yugi makes a few comebacks and ultimately wins using the "Dark Magician" that Pegasus added.
Duke realizes that Yugi plays honestly and determined that he wouldn't have cheated against Pegasus. He starts to worry that the televised game was going to be bad publicity as it made him look like a bad person. However, Yugi and his friends comfort Duke, saying that Dungeon Dice Monsters has the potential to become a great game. Duke soon receives word from Industrial Illusions, saying that they will be helping produce Dungeon Dice Monsters and have agreed to make the game global.
According to his father, Ryuji was born in order to fulfill his father's revenge on Sugoroku Muto. Sugoroku had defeated Mr. Otogi in the Devil's Board Game, causing him to age 50 years in one night.
Ryuji was transferred to Domino High School, where Yugi Muto (Sugoroku's grandson) goes to school. His father used this as an opportunity for Ryuji to defeat Yugi and fulfill the family's revenge.
Ryuji became immediately popular at the school, impressing girls with his dice tricks. Jonouchi grew jealous and confronted Ryuji, who challenged him to a simple card game. Yami Yugi saw how the probability favored Jonouchi losing, despite looking like a 50-50 chance. Dark Yugi then challenged Ryuji to a slightly altered version of the game, where a player has an even chance of winning or losing. To Ryuji's annoyance, Yugi wins twice in this game.
While Yugi and his friends are browsing the Otogi family shop; the Black Clown, Ryuji's father sneaks some merchandise into Yugi's pocket and accuses him of stealing it. After Yugi is taken away by store security, Mr. Otogi takes his Millennium Puzzle and has him put in a room with Ryuji, where he must face him in a game of Dungeon Dice Monsters.
Without the Millennium Puzzle, Yugi was unable to change to Dark Yugi, but managed to do alright in his game against Ryuji, despite having never played before. Mr. Otogi became disappointed in Ryuji's performance and smashed the Millennium Puzzle.
Ryuji got Yugi in a tight spot again, but Yami Bakura talked Yugi into continuing. Yugi defeated Ryuji, who was moved by the game. Ryuji told his father that he cannot make himself hate Yugi and cannot take revenge on him. Mr. Otogi seized Yugi by the neck, with the chain from the Millennium Puzzle and dragged him into another room, telling Ryuji that he failed and no longer has the right to live. After his father's secret room became engulfed in fire, Ryuji took his father out of the way while Yugi re-completed the Millennium Puzzle and then was rescued by Jonouchi.
Duke helps Joey when he collapses from his duel with Yami Marik, and cheers for Yugi during the Battle City finals. He parts with the rest at the end, slipping Serenity his phone number, much to Tristan's anger.
Waking the Dragons
Duke helps Yugi, Joey, and Kaiba against the Doma Organization in the Waking the Dragons arc. He also took part in a duel with Rebecca Hawkins against Valon. Most of this duel, his cards revolved in increasing the strength of Rebecca's dragon monsters. Despite getting a very powerful dragon, Valon beat them with his armor cards. However Duke and Rebecca's souls were not lost as Valon never played the Seal of Orichalcos. Due to being in another place during Yugi and Kaiba's duel with Dartz, he was unable to give the gang support.
KC Grand Championship
He also tags along with Yugi during the KC Grand Championship.
During the final episode he says that he has a date with Serenity and Tristan and Joey attack him for saying it.
During the Dawn of the Duel saga, he helped take care of Yugi's grandpa, and contacted Yugi's friends and other important people such as Maximillion Pegasus about Yugi's absence (offscreen). He came along with Yugi to the Ceremonial battle.
Duke's first Deck is made up of cards that he used in a Duel against Joey Wheeler, in which both duelists agreed to open several packs of cards and simply use whatever they pulled from them. All the cards are from the Pharaoh's Servant expansion of the actual card game.