He is the older brother of Mokuba and the modern-day reincarnation of Priest Seto, himself the original keeper of the Blue-Eyes White Dragon.
Adopted into the Kaiba family as an orphan, Kaiba is at the helm of the world's largest multi-national gaming conglomerate, KaibaCorp, serving as its majority owner and CEO. An intellectually gifted and innovative computer programmer, engineer, and inventor during his youth, he invented virtual software for playing video games as a young child prodigy. Nonetheless, an estranged relationship with his stepfather and outsmarting him auspiciously led the young Seto towards a seamless corporate takeover of KaibaCorp. With access to vast wealth, technological resources, and a wellspring of scientific and business expertise, Kaiba seeks to expand KaibaCorp's business operations not just across Domino City but the entire world. A competitively astute businessman and cutthroat investor, Kaiba is feared throughout the business world; earning him the hospitality and respect that he needs from his peers and rivals. Kaiba also seeks to become the world's greatest player in Duel Monsters, to accomplish this goal, he must defeat his arch-rival, Yugi Muto.
Kaiba is largely considered an anti-hero, as his motives are usually egocentric and his personality traits are selfish and arrogant, but he does sometimes help Yugi and his friends if it's in his best interest (although there are a few occasions where he helps Yugi when faced with a common enemy).
Among one of the recurring plots is Seto Kaiba being forced to deal with either people adversely affected by Gozaburo Kaiba's actions, wanting to take their revenge on Seto himself, or people from within KaibaCorp attempting to take over the company.
Kaiba omits honorifics and has a "rude" pattern of speech. Kaiba uses the word "ore" to mean "I" instead of boku or watashi; ore is a boastful way to say "I" in Japanese. Kaiba usually calls Katsuya Jonouchi (Joey Wheeler) names, such as "bonkotsu" (mediocre), "make-inu" (pathetic dog, loser), "uma no hone" (a nobody), and "zako" (insignificant person, weakling).
Kaiba plays as an arch-rival to Yami Yugi and appears to have a certain snobbish contempt for Yugi's group of friends, namely Joey Wheeler; he disparagingly refers to them constantly with derisive nicknames such as "the nerd herd", "the dweeb patrol", or "the geek squad". At one point, he kept running into them during Waking the Dragons, and quipped "Great. Dork fest continues." In the Japanese version, he is just civil towards them. When he sees Tristan Taylor whose body is taken over by Nezbitt behaves aggressively, he becomes concerned by his change of behavior and tries to reason with him. He's sarcastic, rude, usually selfish, power-lusting, no-nonsense and down-to-earth, and somewhat narcissistic, while he may seem very realistic, but, as Atem has said so multiple times, he can be very clueless. Plus, he is fairly condescending and scathing to everyone, with the exception of Mokuba, the only person he is consistently shown to treat with love and care.
However, it is stated by Mokuba ever since being adopted by Gozaburo, Kaiba has rarely smiled, if at all. Mokuba has also noted he's become much colder than he used to be. Despite this, Kaiba still has strong brotherly instincts for Mokuba and will put his life in danger in a heart beat to safeguard Mokuba's life.
Apart from Mokuba, Kaiba exhibits a compassion for children — especially orphans (as he himself was one and knew what it felt like). Kaiba also threw himself between Zorc and two Egyptian children, thus enabling them to make a getaway. At various points during the series, he opens up momentarily, performing kind acts, though always covering them up with sarcasm, and denying them if asked. These occurrences increase in frequency towards the later series. Aside from that, Kaiba maintains a conservative, stiff, and uptight exterior.
Although Kaiba may seem frigid and unkind toward his brother Mokuba, he is emotionally perspicuous, protective, and exhibits a brotherly love for him. When their adoptive brother Noah had hypnotized Mokuba into not remembering him and thinking Noah was his real brother, Kaiba revealed how much he cared about him to try to make him remember; in one Season 1 episode of the second series anime, after Pegasus is defeated, Kaiba tells Yugi that Mokuba "means everything to me". This is shown when Kaiba risks his own life by standing on a ledge to win the Duel against Yugi so that he can get to Pegasus to save Mokuba. Even when Kaiba preaches that no one gets away with trying to take over his company, he risks KaibaCorp when Dueling Noah for Mokuba.
Kaiba has also had moments of selflessness, such as when he saved Téa from Marik's Rare Hunter without there being any incentive for him to do so.
Kaiba is known for his snobbery and sense of superiority over others, as his motives are usually ruthless and rapacious, and his personality traits are selfish as he would do almost anything to gain status, power, wealth, respect, prestige, glory, and supremacy. As a character, Kaiba is known for displaying a conservative, ruthless, and abrasive demeanor, especially looking down towards people whom he considers socially contemptible or throwing blunt insults and wisecracks towards rival duelists and their dueling abilities to whom he considers to be strategically inferior opponents. Like the Pharaoh, pride is Kaiba's strength and weakness; he never backs down from a challenge and gives everything he can in a Duel. This results him in having a sense of superiority, making it extremely difficult to earn his respect especially towards people he considers beneath him, and causes him to look down on and treat others as inferior until Kaiba considers them as his equal.
This gives him difficulty when forced to rely on others and work as a team. His pride in himself and his accomplishments as an individual are prominent character traits that form a part of his character throughout the series, and he reacts harshly to those who threaten or infringe on it (although it is toned down slightly towards the end of the series).
In addition, Kaiba has expressed dislike, disapproval, and displeasure towards other people using his cards, namely his "Blue-Eyes White Dragon" (his favorite and signature card; notably, he uses its motif to decorate a large portion of his personal effects - e.g., Kaiba Land, his jet, and his clothing). This is shown in Yu-Gi-Oh! - Episode 001, when he rips up Solomon Muto's Blue-Eyes White Dragon after winning it so that it could never be used against him, and also in Yu-Gi-Oh! - Episode 136 when Kaiba becomes very angry when he finds out about Joey using his "Blue-Eyes White Dragon" in their Duel. Kaiba goes so far as to attack Joey's "Blue-Eyes White Dragon" with his own, destroying both in the process, to prevent Joey from using it for another turn. (He even says angrily, "I'm the only one with the skills necessary to wield a Blue-Eyes!" while doing so.) He also despises Pegasus' "Blue-Eyes Toon Dragon", saying it strips the original of all its pride. According to Takahashi, Kaiba's obsession with the "Blue-Eyes White Dragon" stems from the feelings between Kisara (the girl whose Ka housed the Blue-Eyes) and his ancient Egyptian incarnate, Priest Seto. This may also be due to Kaiba's affinity for Dragon-Type monsters.More likely than anything would be it having to do with wanting to have the strongest Deck possible out of any Duelist as part of his domination motif, as he went through great lengths to acquire the three copies he presently has.
One of Seto's recurring traits is his absolute refusal to believe in the magic powers that is often used in the series. Later on he openly admits to believing in all the supernatural events occurring around him, instead of just ignorantly saying they don't exist as he always does (although it is possible that he thinks that it's science instead of magic, and doesn't hesitate to do something about it).
Understandably, Kaiba gains a lot of contempt and disdain from virtually every single person he knows (with the exception of Mokuba) - mostly Joey, Tristan and Tea in particular. Yugi constantly holds out hope for him, as does Yugi's other self Yami. Though Yami himself finds Kaiba's condescending attitude and arrogance quite infuriating. As was shown on the times they've been forced to Duel together as a team. Kaiba, for the most part, could not care less about what they think about him and returns the contempt in kind.
Despite Kaiba's self-centered, snobbish, and elitist personality, he remains an intrinsically obstinate, astute, disciplined and conscientious individual who has a concern for human ethics throughout the entire anime series. He exhibits ethical and morally upright principles in that he is against stealing. Though his plans are often vengeful and Machiavellian, notably vindictive as he sees revenge as a way to get even especially when seeing the negative side of his dueling defeats inflicted by his arch-rival Yami Yugi. Nonetheless, he is a rational, intelligent, and perspicacious person who has a vast belief that hard work and determination is what gets you ahead in life, not stealing at the expense of others to advance your situation. As such, he is disgusted by Zigfried and Noah, calling them pathetic and not worth living up to his company because they were planning on stealing his works to take his company instead of earning it through the trials and tribulations that he went through. Despite his annoyance to Joey, and his intense rivalry with Yami Yugi, he expressed horror when the former was brainwash by Marik to duel the latter in a "death match", as Kaiba says it is not a duel.
Kaiba is also known for his perfectionist mindset and for his disdain of mediocrity as an acceptable standard while maintaining high standards of excellence; whether it's honing his dueling skills or maintaining the quality of his technology. In every duel, he punctiliously implements an array of well executed high power dueling strategies into giving his opponents a hard time to strategically overpower him. He also remains punctilious in the Duel Disks he developed as he would use them even when Duel Rings are nearby by plugging it into the Duel Ring's hologram projector so any card he plays on his Duel Disk is displayed on the Duel Ring instead of just using the Duel Ring.
During Battle City, Seto's main goal is defeating Yugi in a Duel. However, when he lost, he decided on a new path, rather an old one, of building Kaiba Land all around the world. However, he vowed his rivalry with Yugi is far from over, even though they never had an on-screen Duel after this. At some point, Kaiba through his philanthropic hospitality and passion for Duel Monsters established the Central Duel Academy, a private educational institution to train the next generation of up and coming duelists to accomplish this goal.
Kaiba has proven himself one of the most astute, accomplished, and formidable businessmen and investors in the world. A child prodigy and polymorphic genius, he excels at virtually any skill or area of study he applies himself to. With natural aptitude and raw talent, since his teenage years, he has both successfully reinvented and ran his world-wide corporation, while also pursued his passion for games, having spent years as an undefeated world champion in various games including Duel Monsters and chess. In addition to his shrewd business acumen and gaming aptitude, while having no known university degrees, Kaiba is incredibly skilled with science and technology, most noticeably programming and engineering. He specializes mainly in computer software programming and building cutting edge technological software and hardware such as the development of KaibaCorp's high-tech Duel Disks and advanced Solid Vision technology. He is very advanced hacker, skillfully making his way through the Duelist Kingdom network. He is also very athletic, able to nimbly land from high jumps and a proficient hand-to-hand combat, easily defeating some of Pegasus' elite guards while showing deceptive raw strength.
Yugi Muto/Yami Yugi
After Kaiba lost to Yugi in their first Duel he makes a conviction to vanquish Yugi and becomes his arch-rival throughout the series. Their differing personalities often causes them to come into conflict with each other such as their initial meeting with Kaiba's belief in cards being meant for power over Yugi's belief that cards have a heart. Despite their differences, Yugi bears no animosity towards Kaiba, which cannot be said the same for the other way as Kaiba holds a grudge against Yugi throughout the entire series as he seeks to become the world's greatest player in Duel Monsters but is unable to grasp the fact of being overshadowed by Yugi as his second. Throughout the series, circumstances bring Kaiba and Yugi together when the two cross paths to fight back against common foes such as Yami Marik and his Rare Hunters, the Big Five, Dartz, and Thief King Bakura. Yugi respects Kaiba as a Duelist, a sentiment that Kaiba seems to share. When Kaiba discovers that Yugi Muto and Yami Yugi are two different people, Kaiba focuses his rivalry on the latter for past defeats. However, he still respects Yugi as a Duelist in his own right. This is shown at the start of the Ceremonial Battle when Kaiba described the Duel (to himself) as the ultimate Duel for the title of Duel King, acknowledging Yugi Muto as Yami's equal.
Joey Wheeler
At the start of the series, Kaiba expresses his dislike, animosity and contempt of Joey Wheeler, one reason for being Yugi's close friend and the other for his consideration of Joey's lack of duelling experience. In particular, Joey dislikes Seto's arrogant and snobbish behavior and likewise fuels Kaiba's contempt for Joey as he considers him a third-rate and inferior Duelist throughout the course of the series. The difference in their skill levels is displayed in Duelist Kingdom and Battle City with Kaiba ousting Joey and winning both duels, although with significantly more effort on the second duel. Later, Kaiba considers respecting Joey as a Duelist after Joey withstands The Winged Dragon of Ra's attack initiated by Yami Marik, although he regards Joey with contempt and disparages his dueling abilities in the tournament, both when fighting for 3rd place and in his match with Yami Yugi, respectively. In Waking the Dragons arc, Kaiba was considerate enough to prevent Joey's soulless body from falling off of Tristan's back resulting Joey in turn gaining enough respect for Seto to actively root for him in Seto's match against Zigfried.
Over time, Kaiba starts to develop a certain degree of respect towards Joey's dueling skills. Mokuba mentions that KC DuelTek 760 is programmed to apply dueling styles of various best Duelists, Joey included. This causes Tristan to joke that the computer relies on luck, much to Joey's annoyance. Kaiba is impressed and amused witnessing Joey's Duel with the corrupted former Kaiba Corp legal advisor, although he masks them with sarcasm. Furthermore, Kaiba is clearly disappointed that Joey loses against Valon, causing the former to lose his soul. Kaiba is also gracious enough to enlist both Yugi and Joey to fight alongside him against the Great Leviathan, and invites both of them to participate in the Grand Championship.
Ishizu Ishtar
Ishizu first meets Kaiba at the Domino City Museum when she personally invites him for a private exhibition regarding the opening of her highly anticipated Egyptian exhibit through a televised press conference invitation. With her belief in the nature of fate, she felt that it be destined that the two would cross paths. Ishizu then gives Kaiba a private showcase of never seen before artifacts depicting the origin of Duel Monsters as well as the secret of the Egyptian God Cards. She then postulates to Kaiba of starting a Duel Monsters competition in order to help draw out the Rare Hunters in the open as well as offering him Obelisk the Tormentor to borrow during the duration of the tournament.
During the Battle City tournament, Ishizu attracts Kaiba's attention during her first and only duel against him as she flawlessly predicted Kaiba's every strategic move and causing him to squirm. During the duel, Yami Marik similarly parallels Kaiba's struggle against Ishizu with his own childhood experience of being stringed and taken down by Ishizu in the past with her Deck. Ishizu gracefully manipulated every move he made and foiled his strategies causing her to toy with Kaiba's mind nearly humiliating him with a loss. Though Ishizu lost the duel, the loss taught her a valuable lesson of the greater importance regarding the nature of destiny as it gave her hope for changing her brother's future relying on the wisdom and strength of the people around her, in particular for her concerns toward Kaiba for eventually helping her brother Marik eradicate his other evil half trapped within.
As the Battle City tournament drew to a close, Ishizu's selfless soliciting for the well-being of Kaiba through her desire to rescue her brother requests him to be present for the final duel of the Battle City tournament in order to assist Yami Yugi in fulfilling his dueling destiny by defeating Yami Marik. Anxious to cultivate his aid to help Yugi rescue her brother, the young Ishizu solicitously convinces the reluctant and selfish Kaiba to help Yami Yugi win the final duel, where the eventual outcome of it will depend on the salvation of the world and impact the future of mankind. She then explains to Kaiba that the destiny of the latter is to contribute to the triumph of light, and that, in antiquity, he was, indeed the Pharaoh's adversary, but also a friend who constantly challenged him to push him to improve. She warned Kaiba that walking away from the tournament is a huge mistake and forewarned that his entire future is at stake. Concerned about Kaiba's reputation for his obstinacy, Ishizu scolds Kaiba for his selfishness and hesitance in helping Yami Yugi as well as denying his ancient Egyptian heritage by reasoning with him stating that he'll suffer the consequences and the fate of the entire world will suffer as a result of his obstinate stubbornness by turning back on mankind. She also lectures Kaiba that he was destined to organize the event guided by a force beyond his control and how his modern day rivalry with Yugi has been in existence for thousands of years. In addition, Ishizu also informs Kaiba about how his rivalry with Yugi as his past incarnation as as a skilled sorcerer who constantly challenged the Pharaoh and with the sorcerer's help, the Pharaoh was eventually able to save his own people. Much to Kaiba's consternation, Ishizu's solicitous coaxing to cultivate Kaiba's assistance eventually convinced him to give one card to help Yami Yugi take down Yami Marik's Winged Dragon of Ra.
Mokuba Kaiba
Being his brother, Seto cares for Mokuba and is perhaps the one person he actually cares about. When Mokuba was kidnapped by Pegasus, Seto went to get him back and would not stop until his brother was safe. Even after Pegasus took Mokuba's soul, Seto still tried to get him back, but refused to battle or hurt his brother. Eventually after Yami Yugi defeated Pegasus, Seto and Mokuba were happily reunited at last and went home.
Deck
Kaiba's signature cards are his three "Blue-Eyes White Dragons" and the Fusion Monster formed from the three dragons, the "Blue-Eyes Ultimate Dragon", all of which serve as the key boss monsters to Kaiba's Decks throughout the series. His decks primarily rely on a Beatdown strategy to aggressively overwhelm his opponents with a roster of monsters with high attack. His cards are intended to be pugnacious, bellicose and vicious to reflect Kaiba's serious, stiff, and uptight personality.[160] During Duelist Kingdom, Kaiba's Magic and Trap cards supplement this strategy by disabling opposing monsters, such as "Shadow Spell" or "Defense Paralysis" to stop his opponent from gaining any advantage against him. Kaiba also uses a combo of "Saggi the Dark Clown" and "Crush Card", destroying all monsters in his opponent's Deck with more than 1500 ATK, further inhibiting their ability to defend against him.
During Battle City, Kaiba added "Obelisk the Tormentor" to his Deck, along with more Virus Cards like "Giant Germ" and "Virus Cannon". He also began using Machine-type and Machine-type support cards such as the XYZ Union monsters, "Enemy Controller" and "Interdimensional Matter Transporter", contrasting Kaiba's trust in technology against Yugi's Deck of mystical monsters like the "Dark Magician". Kaiba continues to make use of his "Crush Card Virus" but instead of "Saggi" prefers "Shrink" to weaken high powered monsters and Tribute them. Another combo he is fond of at this time is "Ring of Destruction" and "Ring of Defense" to destroy enemy monsters and damage his opponent's Life Points.
Kaiba adds the Pyramid of Light to his Deck, using it to remove Yugi's Egyptian God Cards from play. He then depletes Yugi's Deck with a combo of "Peten the Dark Clown" and "Deck Destruction Virus", and utilizes another enhanced form of his "Blue-Eyes", "Blue-Eyes Shining Dragon".
While in the Virtual World Kaiba's Deck had a stronger focus on Dragon-Type monsters, adding "Spear Dragon", "Different Dimension Dragon" and "Thunder Dragon.
Kaiba gained the "Fang of Critias". His Deck still focused on the "Blue-Eyes" and other Dragons, adding "Paladin of White Dragon".
After Waking the Dragons, Kaiba only Dueled twice more in the series, against Zigfried von Schroeder in the Grand Championship, and later against Yami Bakura. Against Zigfried, Kaiba focused on removing his cards from play then returning them to the field with "Dimension Fusion" in masses and using cards to regain Life Points such as "Soul Absorption" and "Emergency Provisions" to counter the high costs of these cards. Kaiba also incorporates more dragons most notably the "Chaos Emperor Dragon" and uses its ability to devastate his opponent. He makes his duel finale against Yami Bakura, where he once again relies on his "Blue-Eyes" and uses cards seen in previous seasons to summon it to no avail as the duel is called off resulting in an undecided outcome.
Trivia
The song "You're Not Me" is based on Kaiba.