Together with the spirit of Pharaoh Atem, he holds the title "King of Games" (King of Duelists in Japanese version).
Yugi possessed the three thousand-year-old (five thousand in the dub) mystical Millennium Puzzle, which allowed his body to bear host to the spirit of the Puzzle, Yami Yugi. Yugi was initially unaware of his existence and control of Yugi's body, and would involuntarily shift to Yami Yugi at trying times.
He lives with his paternal grandfather, Solomon Muto, and his mother.
Yugi is part of a close-knit group of best friends: Joey Wheeler, Tristan Taylor, Téa Gardner and Bakura Ryou. Yugi's friends often cheer him on from the sidelines, and Joey has dueled at his side. Yugi has been friends with Téa since childhood and has a romantic crush on her. Téa has been shown to have romantic feelings for both Yugi and Yami Yugi.
Yugi is kind-hearted and child-like. He is good at games, riddles, and puzzles, especially Duel Monsters. As Shadi stated when he looked into Yugi's Soul Room, he has no malice or wickedness in his heart.[9] This doesn't mean he cannot get angry at someone, but is willing to forgive them.
Yugi is also very shy when comes to meeting people who admire him, especially girls. As seen with the cases of Mai, Vivian, and later Rebecca, he would often blush and even freeze up when they approached him. Yugi is also not good in front of big crowds, as seen when Mokuba tried to get him up on stage to give a speech.
Unlike his other self, Yugi has no problem with losing. In fact, he is willing to lose if it means helping his opponent. Yugi also has a lack of confidence in his own abilities, but still wants help out his friends. Over the course of the series, he becomes more confident and determined. He is also willing to sacrifice himself if it means saving someone else, such as Joey or Yami Yugi.
Relationships
Joey Wheeler
Joey initially bullied Yugi along with Tristan, but after he saw how Yugi stood up to Ushio, they became best friends. When he was possessed by Marik, Yugi took Yami's place to get his friend back to his senses. After Joey's first Duel with Marik, Yugi took it hard, cried, blamed himself, and was in grief. Joey, likewise, was upset when Yugi's soul was taken by the "The Seal of Orichalcos". Joey is fiercely loyal to Yugi and is often quick to give his support to him. Joey is the most precious person to Yugi; they love each other, are best friends, and would do anything for each other. Tea states that Yugi and Joey are like brothers,[168] which emphasises how close the two are and how much they love each. During the Ceremonial Battle he was the first to declare his support for Yugi over Yami.
Yami Yugi/Pharaoh Atem
After putting the Millennium Puzzle together, a "walk-in" spirit entered his mind and bonded with him. Yugi was initially unaware of Yami's existence and control of Yugi's body would involuntarily shift when Yugi or his friends are wronged. After finding out about the spirit, he was afraid of him, but eventually grew to accept this revelation as well as Yami himself. Not only did the two become best friends but also developed a bond similar to that of brothers or a father and son. As Yugi began to grow, becoming stronger he still remained in Yami's shadow.
After the warehouse fire, Yugi is shown to be afraid of losing Yami. When he found out Yami was looking for his lost memories, Yugi decided to help, even though it meant they would one day be separated. Yugi was heartbroken as he watched Yami using the Seal of the Orichalcos, but when he lost and was about to lose his soul, Yugi sacrificed himself to save his closest friend who for the 1st time seen in the series cried.
After winning the Ceremonial Battle, Yugi was upset to see him go, claiming that he was weak and wasn't ready. Yami, proud of him, tells him otherwise, and as he steps through the door to the afterlife, Yugi gives him a thumbs up, now ready to go on his own.
Téa Gardner
Téa has been Yugi's friend since childhood. Téa is in love with Yugi, but no one knows if she loves Yugi more than his other half. The fact that Yugi and Yami Yugi are two separate beings causes her confusion as to who she really loves. Though it seems her deepest feelings reside toward the original Yugi, as it is shown in many episodes when Rebecca Hawkins hugs Yugi, Téa appears upset, though this is before she accepts that Yugi and Yami are separate people. She has also shown jealousy towards Mai Valentine for her initially flirtatious attitude towards Yugi during her first appearance at Duelist Kingdom, as well as Vivian Wong.
Tristan Taylor
Tristan initially bullied Yugi along with Joey, but after he saw how Yugi stood up to Ushio, he became a friend to him. While his friendship with Tristan is not as strong as Joey or Yami/Atem, Tristan is still a good friend of Yugi who, just like Joey, looks out for Yugi and the gang. Tristan has on occasion lent his cards to Yugi to help in a Duel such as Cyber Commander in his first Duel with Yami Bakura. When Tristan was possessed by Bakura, he almost killed Téa, Joey, and Yugi (sent to the Shadow Realm in the dub). But when he met up with them again the others were hostile towards him but Yugi knew Tristan better than to attack the three.
Seto Kaiba
After Seto Kaiba lost to Yugi in their first Duel, he becomes determined to defeat Yugi and becomes his rival. 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/Yami'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 held a grudge against Yugi for quite some time. He even cheered Kaiba on when the latter played a match against Pegasus even though Kaiba had taken Yugi's star chips by threatening to jump off the edge of the castle unless Yugi stopped an attack that would have won him the Duel, something that made Yugi suffer a loss in confidence due to nearly killing Kaiba and that Kaiba truly loathed Yugi.
When Kaiba ultimately lost to Pegasus he had his soul taken away. Yugi became outraged at Pegasus for playing games with their lives. He and Yami made it their mission to free Kaiba along with Mokuba Kaiba and Yugi's grandfather. Kaiba helped Yugi find his friends when they were abducted by Marik. Usually circumstances force Kaiba to work with or aid Yugi such as common foes like Marik and his Rare Hunters, the Big Five, or Dartz. Yugi respects Kaiba as a Duelist, a sentiment that Kaiba seems to share. When Kaiba discovers that Yugi and Yami Yugi are two different people he 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 as Yami's equal. When Yugi defeats all three God cards Kaiba openly states he believes Yugi can win. Yugi considers Kaiba to be a friend.
Before they traveled to Egypt, Yugi and Yami reflect on their journey until that point, Yugi muses on all the friends he made because of Yami, and Kaiba appears along with his other friends.
Rebecca Hawkins
Initially, Rebecca was hostile to both Yugi and his grandfather, accusing them of stealing her grandfather's "Blue-Eyes White Dragon", but this conflict is resolved very quickly. However, during her second appearance in the Waking the Dragons arc, Rebecca announces that she is in college and has taken Yugi as her "boyfriend". Since then, Rebecca continues to express her romantic affection for Yugi, getting angry at Yami Yugi after his loss to Rafael. The two even share a bit of a moment at Rebecca's destroyed house. She also gets mad at Vivian when she tries to flirt with Yugi, and taunts her after beating her in a Duel. Then, during her Duel with Leon von Schroeder, she gets depressed when Yugi gets distracted by having to find his grandfather, who goes missing, and hugged him pretty much whenever she saw him.
Yugi's Decks are most famous for his "Dark Magician". Yugi's Deck probably has the most variety and balance of any other character's Deck in the series, and is sometimes referred to as a Strategy Deck. His original Deck mostly composed of low Level EARTH and DARK monsters, which he supplements with Magic Cards to perform effective combos. The Deck also had Exodia in it, which he used in the first episode to defeat Kaiba, but Weevil Underwood threw them overboard on the ship to Duelist Kingdom, and Joey Wheeler was only able to recover two of them, so Yugi abandoned Exodia.
During Battle City, he keeps the theme of having EARTH and DARK monsters and adds more control cards to the deck which allow him to manipulate an opponent's cards, such as "Brain Control", "Lightforce Sword" and "Mystical Refpanel". During this time Yugi debuted his Magnet Warriors, Royal Knights, and "Dark Magician Girl", which would become mainstays in his Deck for the rest of the series, and included more Effect Monsters. He also includes more support for the "Dark Magician", such as "Magical Dimension" and "Diffusion Wave-Motion". Yugi's Deck contains Joey's "Red-Eyes Black Dragon" after he wins it from the Rare Hunter, but he eventually returns it to Joey. Aside from the Red-Eyes and the Egyptian God Cards he acquires during the tournament, Yugi's rarest card is "Dark Magician". Yugi's Deck mostly focuses on Warrior and Spellcaster-Type monsters, contrasting Seto Kaiba who uses Fiend and Dragon-Type monsters, or cards with a technological theme to them.
As the series progressed Yugi's Deck would continue to evolve to have greater focus on the "Dark Magician" and its related cards, adding "Dark Renewal", "Sage's Stone" and "Dark Magic Curtain" to the Deck.
During the Dawn of the Duel arc, Yugi uses a Deck separate from Yami Yugi's, which is based around cards with a Toy theme like "Blockman" and the "Gadgets", and Level monsters that grow stronger over time, such as "Silent Swordsman" and "Silent Magician". This Deck represents the strength Yugi has without the help of Yami Yugi as well as his playful side. As a result he does not use the Dark Magician and its related cards, leaving them to Yami Yugi when they build separate Decks for the final Ceremonial Duel.
When Yugi's Deck goes on tour at Duel Academy, the Copycat Duelist Dimitri steals it and copies Yugi's voice, mannerisms and Dueling style. While Dimitri copies Yugi's moves very well, he loses because he lacks the bond with the cards that Yugi has. This Deck is based around the "Dark Magician" and retrained "Chaos" variants of Yugi's Ritual Monsters.