Twelve-year-old Shobu Kirifuda has one goal: to become a top-ranking player at the game of Duel Masters, a card game in which players use spells and summon monsters to break through their opponents' shield cards and subsequently defeat them. Shobu believes he's a great player, but he soon discovers that there is more to the game than he originally thought; true Duel Masters, he learns, are able to make the monsters on the cards manifest themselves during a duel. A mysterious group has taken a keen interest in Shobu, although their reasons are as mysterious as the group itself. Now Shobu and his friends not only have to win the championship, but also try to figure out who these people are and why they're so interested in Shobu.
Ever since Yugi Mutou completed the Millennium Puzzle his life has changed; he's made friends, learned how to play the card game Duel Monsters and has gained more confidence in himself. After his grandfather is beaten in a duel he is challenged by Seto Kaiba, ranked number two in the world, but Yugi beats him regardless. Now, as a result of his victory, Yugi has attracted the attention of the game's creator, Pegasus. Yugi is then challenged to a dual in an alternate reality where magic brings the monsters to life, but is beaten and his grandfather's soul is taken. In order to retrieve it Yugi must now participate in a tournament against the best duelists in the world, defeat the game's creator, and learn more about the secrets within his Millennium Puzzle!