Ryou Bakura is a recurring character known as the keeper of the Millennium Ring. A transfer student who becomes a friend to Yugi Muto and his circle, Bakura shares Yugis interest in games, with a particular fondness for tabletop role-playing games like Monster World. He is polite, gentle, and somewhat socially awkward, often presenting a calm and light-hearted demeanor. However, beneath this surface lies a deep-seated loneliness and sorrow, stemming from a difficult past. Before meeting Yugi, Bakura was forced to change schools frequently because the people who played games with him would inexplicably fall into comas. It is later revealed that this was the work of a malevolent spirit residing within the Millennium Ring, an ancient artifact his father purchased on a trip to Egypt. This spirit, known as Yami Bakura or Dark Bakura, would take control of Bakuras body and trap the souls of his friends in his game pieces.

The central conflict of Bakuras character is his relationship with this dark entity. Unlike the cooperative bond between Yugi and his other self, Yami Bakura is a malignant presence that completely suppresses Bakuras soul when it takes over, leaving the host with no memory of the events. This dark spirit is driven by a millennia-old vendetta and a desire to acquire the Millennium Puzzle, often serving as a main antagonist. Despite the immense danger it poses, Bakura continues to wear the Millennium Ring, driven by a deep and innocent curiosity about its history. This trusting nature, combined with the spirits ability to perfectly mimic him, frequently allows Yami Bakura to act within the group without raising suspicion. Bakura also carries the sorrow of a family tragedy, as his younger sister, Amane, died in a car accident, and he is often seen writing letters to her in heaven.

Bakuras role in the story varies significantly between adaptations. In the original manga and first anime series, he is a close friend of the main group and actively joins them on their adventures. In the more widely known second anime series, his role is greatly reduced; he is often controlled by his dark half and does not accompany the group as frequently. While Yami Bakura is the one who typically duels, using an Occult deck focused on disruption and graveyard manipulation, it is stated that the deck itself was built by the gentle Bakura, who has a fondness for macabre and gross monsters. One of his and the spirits favorite cards is Change of Heart, a card that allows control over an opponents monster. The spirits abilities extend beyond dueling, including the power to initiate Shadow Games, trap souls within objects using a technique called Parasite Mind, and bring Duel Monsters cards to life. Though often a victim of circumstance, Bakuras quiet endurance and his complex, tragic connection to his other self are central to his character. He stands as a foil to Yugi, demonstrating how sharing ones body with another spirit can be a curse rather than a gift.