Ryo Bakura is introduced as a new transfer student at Domino High School who quickly befriends Yugi Mutou and his circle of friends. He is a polite, soft-spoken, and somewhat socially awkward young man who shares Yugis deep passion for games, with a particular fondness for tabletop role-playing games like Monster World. His appearance is distinctive, characterized by his white hair and typically gentle demeanor. Unbeknownst to him, Bakura is the bearer of the Millennium Ring, an ancient Egyptian artifact that he received from his father who purchased it on a trip to Egypt.

Within the Millennium Ring resides a malevolent spirit known as Dark Bakura or Yami Bakura, who serves as a primary antagonist throughout the story. Unlike the symbiotic relationship between Yugi and his other self, the spirit of the Ring is purely evil and seeks to possess all seven Millennium Items to unlock a great and destructive power. This dark entity completely suppresses Ryo's consciousness when it takes control of his body, and the innocent host is often left with no memory of the spirit's actions. The relationship between the two serves as a dark foil to the bond shared by Yugi and the Pharaoh. While Ryo is kind, gentle, and values his friendships greatly, Dark Bakura is sadistic, ruthless, and manipulative, viewing his host as a mere vessel to be used and discarded.

Bakura's personal history is marked by tragedy, as he lost his younger sister, Amane, in a car accident, and he is often seen writing letters to her. This loss contributes to a sense of loneliness and a deep-seated need to belong, which makes his friendship with Yugis group all the more important to him. Despite the danger, he remains curious about the Millennium Ring, a trait that the evil spirit within readily exploits. Throughout the series, his role in the main cast is frequently that of a hostage or a victim, as Dark Bakura uses his body to infiltrate the group and advance his own schemes, such as trapping their souls in cards or RPG figurines.

Dark Bakura's motivations are rooted in a 3,000-year-old grudge from ancient Egypt. He is revealed to be the combined essence of the Thief King Bakura, the sole survivor of the slaughtered village of Kul Elna, and the Great Evil God Zorc Necrophades. His ultimate goal is to resurrect Zorc and plunge the world into darkness, seeking revenge on the Pharaoh whom he blames for his village's destruction. In the present day, he is a cunning and patient chessmaster, setting elaborate traps and forming temporary, treacherous alliances, such as the one with Marik Ishtar during the Battle City tournament, to gather the Millennium Items.

Ryo Bakura himself demonstrates notable abilities, particularly his intelligence and strategic mind. He possesses a keen understanding of games and is often the first to grasp complex strategies during duels, acting as a perceptive commentator from the sidelines. He also shows moments of profound bravery and determination, willing to sacrifice himself to thwart the evil spirit that plagues him. Dark Bakura, in contrast, is a formidable and versatile opponent. He is a master of Shadow Games, capable of trapping souls and enforcing Penalty Games. As a Duelist, he favors an Occult or Fiend-themed deck, employing disruptive strategies and alternate win conditions, most famously the Destiny Board, which reflects his methodical and cruel nature. His true power is rooted in his ancient Ka, Diabound, a monstrous creature that grows stronger by absorbing the abilities of its defeated foes.