Seto Kaiba

In his introduction, Kaiba discovers that the grandfather of his classmate, Yugi Mutou, owns the rare Blue-Eyes White Dragon card. Dark Yugi emerges from within Yugi's Millennium Puzzle to challenge Kaiba a Shadow Game to reclaim it. Kaiba is defeated, suffering Dark Yugi's Penalty Game: Experience of Death (死(し)の体感(たいかん), Shi no Taikan).[7][8] Kaiba plots a revenge. He acquires the other three Blue-Eyes White Dragon cards in existence through extortion and blackmail and builds "Death T," a "theme park" made up of many deadly games designed to end the lives of Yugi and his friends. He defeats Sugoroku and tears up his Blue-Eyes White Dragon and subjects him to an artificial Penalty Game that mimicked his own, forcing Yugi to participate in Death-T or else he will kill his grandfather. Yugi once again defeats him and uses the power of his Millennium Puzzle to subject Kaiba to a Penalty Game, leaving him in a coma.[9][10]

Duel Monsters creator and Millennium Eye wielder Maximillion Pegasus schemes to take control of Kaiba Corporation (海馬コーポレイション, Kaiba Kōporeishon) from Seto by conspiring with its board of directors, the Big Five, and abducting his brother Mokuba. After Kaiba wakes up from his coma, he gets wind of Pegasus' plans and his kidnap of Mokuba, and travels to Duelist Kingdom. Kaiba regains his deck and briefly battles Jonouchi. Kaiba and Yugi later play the game atop the castle parapets. Kaiba is once again on the cusp of defeat, until he places his own life on danger by balancing on the edge of the turret, forcing Yugi into a moral corner. Dark Yugi nearly kills Kaiba, but Yugi forces him to forfeit the game in fear of killing his opponent. Kaiba goes on to duel Pegasus, but is overcome by the power of his Millennium Eye and is defeated. Pegasus gives Seto Kaiba the Mind Card Penalty Game, sealing his soul into a card, but when Dark Yugi defeats Pegasus in a Shadow Game during the final round of the tournament, the Kaiba brothers are both freed from their Penalty Games.

In the Battle City arc, Kaiba is summoned to the Domino City museum by Egyptologist Ishizu Ishtar, Kaiba is shown the ancient stone tablet that depicts a battle between what appears to be his past self and the Pharaoh. He is interested in her tale of the God Cards – three powerful one-of-a-kind cards that Pegasus had entrusted to her. Two, however, were already stolen by her brother Marik and his Ghouls organization, and she gives the third – God of Obelisk – to Kaiba, encouraging him to hold a tournament of his own to lure in Marik and his organization of the gaming underworld, who he views as counterfeiting scum that deserve to be crushed. Seeking to obtain the remaining two God Cards for himself and eliminating the organization of bootleggers, Kaiba agrees, and begins his "Battle City" competition.[11] During the tournament, Kaiba teams up with Dark Yugi to rescue Mokuba and Yugi's friends from the clutches of Marik and his deadly games. Afterward, Yugi, Kaiba and Jonouchi enter the finals, unaware that Marik has made a deal with Dark Bakura, and he, along with Marik and Marik's stepbrother Rishid, are registered as well. Kaiba trumps Ishizu's prophecy of defeat and claims victory.[12] Kaiba faces Yugi in the semifinals, and the two unleash their God Cards against the other.[13] Yugi manages to defeat Kaiba and go on to the final battle against Dark Marik. Kaiba gives Yugi the card Fiend Sanctuary prior to the duel, and with it, Yugi is able to hold off the attacks of Dark Marik's Sun Dragon Ra and defeat him in his Shadow Game.[14]

Shortly after his return from the Duelist Kingdom, the Big Five attempt to appease an outraged Kaiba by revealing that they have finalized his virtual reality game software, and invite him to test it out for himself. However, this was another attempt to do away with Kaiba, but Yugi and his friends manage to rescue him. The Big Five log into the virtual world in an attempt to stop them from escaping, but they are defeated in a duel, and their own minds became trapped in the virtual reality program. Some time later, in the midst of the Battle City tournament, the Big Five's digital consciousnesses are discovered stranded in cyberspace by a mysterious boy named Noah, who recruits them for a revenge campaign against Kaiba. Noah admits to being Gozaburo Kaiba's biological son, and claims his mind exists as a computer program after he was fatally wounded as a child and later digitized. After Noah is defeated, Gozaburo reveals himself as alive and inside the Virtual World, and sets a series of orbital missiles to launch and destroy the world. While Kaiba stops Gozaburo, a reformed Noah reprograms one of the satellites to attack the main computer database and helps Yugi and his friends escape.

In Season 4 of the anime, Kaiba, along with Jonouchi and Yugi, is one of three duelists chosen to fight the Atlantean King Dartz. During the season, Kaiba meets Amelda, an orphan whose brother and parents were killed by KaibaCorp-owned military forces under Gozaburo Kaiba's command. Due to his love for his brother, Kaiba becomes sympathetic to Amelda and carries his soul-less body to safety after their duel. Kaiba and Dark Yugi eventually duel Dartz, and although Kaiba loses, Dark Yugi defeats Dartz and Kaiba is restored, taking part in the battle against the Great Leviathan.

In the first half of season 5, KaibaCorp's stock prices are at an all-time low as a result of a failed takeover by Dartz, and when Kaiba hosts a tournament to restore the company's reputation, Zigfried von Schroeder infiltrates it and hacks Kaiba's computer systems. Catching Zigfried, Kaiba dispatches him a duel. However, Zigfried has his brother Leon duel Yugi in the finals. During the duel, Zigfried tricks Leon into activating Golden Castle of Stromberg, releasing a computer virus into Kaiba's system and forcing Leon to attack and thus forcing his hand. However, Yugi prevails while Kaiba, who anticipating such a plan, has already had his computer systems backed up.

Seto Kaiba's only appearance in the original manga version of the Millennium World arc is in the last chapter. Although Seto Kaiba does not take part in the Shadow RPG during the Millennium World arc of the manga, in the anime, Dark Bakura gives him the Millennium Eye, which begins to show Kaiba visions and convinces him to fly to Egypt to determine if they are real or not. During the final battle, he is able to hold his ground against Zorc. In the original Japanese anime, Kaiba eventually does acknowledge his past and the events that occurred in the Memory World Shadow RPG.

Seto Kaiba is the main antagonist of the Yu-Gi-Oh! movie, which was produced by Toei Animation in 1999. In this film, Kaiba, learns about Shougo Aoyama's Red-Eyes Black Dragon, organizes a tournament where strong duelists are invited - and attendance is mandatory. Shougo and Yugi Muto are later chased down and roughed up by Kaiba's henchmen from KaibaCorp, with Kaiba's henchmen overpowering both of them and stealing Yugi's Millennium Puzzle. Now Yugi must enter Kaiba's tournament and show Shougo that one can have both the potential and the power to become a true Duelist. After the game, Kaiba tells Yugi that their battle is not over yet, informing Yugi that he is the only one in the world worth fighting as he leaves the arena. [15]

Kaiba makes an appearance in Yu-Gi-Oh! The Movie: The Pyramid of Light. In the wake of his defeat at the Battle City Tournament, Seto began to suggest a means of defeating the three Egyptian God Cards that Yugi now holds, in order to defeat him and reclaim his title as world champion. His quest led him to Pegasus, theorizing that Pegasus would not have created the Egyptian God Cards without creating some means of destroying them. Wagering his three Blue-Eyes White Dragons against the card that Pegasus promised him, Kaiba succeeded in winning their duel, only to find two cards within Pegasus's deck that could accomplish what he sought. Kaiba challenges Yugi to yet another duel in his Duel Dome, and put the first of the two cards into play – the enigmatic "Pyramid of Light," which prevented the Egyptian God Cards from participating in the battle. As the duel proceeded, however, it was revealed that Kaiba had been used as a puppet for the ancient Egyptian sorcerer, Anubis, who had placed the Pyramid of Light card in Pegasus's deck. The Pyramid's powers were draining the lifeforces of Yugi and Kaiba as the duel progressed, eventually resurrecting Anubis, who dispatched Kaiba and took his place in the duel. With Kaiba's aid, however, Yugi put the second mighty card into play – the Blue-Eyes Shining Dragon, able to destroy any card in play. The Shining Dragon destroyed the Pyramid of Light, and later wiped out Anubis.[16]

Kaiba has commissioned an excavation to retrieve the disassembled Millennium Puzzle from the ruins of the Millennium chamber. The item had previously housed the spirit of his longtime rival, Pharaoh Atem, whom he hopes to "return to life" in order to settle their ancient score. The excavation is interrupted by Diva, who faces Kaiba in a game of Duel Monsters and steals two pieces of the recovered Puzzle. He keeps one fragment and gives the other to his younger sister Sera, who passes it on to Yugi Muto, as he is the only one who can reassemble the Puzzle, being host of the Nameless Pharaoh. Kaiba has a computer that rebuilds the Millennium Puzzle and discovers the last two pieces are missing. He abducts Diva and approaches Yugi, so he can have the two take part in the showcasing of his updated Duel Disk virtual reality technology. He intends to duel both Diva and Yugi, while gambling their pieces of the puzzle. However, Yugi is furious with Diva over what he did to Bakura and insists he duel him instead, which Kaiba agrees to. Yugi defeats Diva, resulting in Bakura's return to reality, and while dueling Kaiba, Yugi re-completes the Millennium Puzzle to demonstrate that the spirit of Atem is no longer inside it. Diva becomes corrupted by the incredible evil powers of the Millennium Ring, and duels both Yugi and Kaiba. Kaiba sacrifices himself during the Duel and makes a final plea for Yugi to call forth Atem. Yugi succeeds in doing so, and he and Atem defeat Diva with ease. Atem and the Millennium Puzzle then fade away, and Kaiba and everyone else return to reality. The film concludes with Kaiba using his technology in conjunction with the Quantum Cube to transport his own consciousness to the Afterlife and face Atem.[17]

Though not seen much in the Yu-Gi-Oh! GX series. Kaiba is referred as the one who owns and started Duel Academy (Duel Academia) and named the dormitories personally. He has made several appearances, the first being when he makes a bet on his ownership of the school. Another few times were in flashbacks, once where Jaden remembers a competition he entered that was held by the KaibaCorp and another when a reporter sneaks into Duel Academy. The Duel Spirit Kaibaman also appears. Kaiba's only appearance in person comes when Sartorius visits him to request the use of his Kaiba Land amusement park. Kaiba has not made any other appearance since, though it has been shown that he is the only surviving citizen of Trueman's invasion in Domino City. The Kaiba Dome is seen often in Yu-Gi-Oh! 5D's. His company Kaiba Corp is responsible for turning Domino City into New Domino City.

Kaiba also appears in some of the Yu-Gi-Oh! video games as an opponent which the player can duel (or play as) as well as the crossover Jump Force.[18]