Movie
Description
Rua, known internationally as Leo, is Luna's twin brother sharing residence in New Domino City's Tops district. Their parents' frequent work absences leave the siblings largely self-reliant, educated via online schooling. Rua displays a lively, sometimes clumsy personality, yet proves perceptive and serious when needed. He deeply cares for his sister, often rotating his hand excitedly when animated, and unconsciously took on the role of her protector while she safeguards the Duel Monsters Spirit World.

He first encountered Yusei Fudo by sensing his distress, aiding his rescue after Yusei's duel with Trudge. Rua persuaded Yusei to stay overnight by initiating a duel, awakening to find Yusei had modified his and Luna's Duel Disks for their smaller arms. When Luna declined her Fortune Cup invitation, Rua disguised himself as her to compete, dueling Greiger and losing after a hard-fought match. During Luna's consolation duel against Professor Frank, Rua fell into a hypnotic trance alongside her, later revealing his self-appointed protective duty.

Learning of the Signers and their conflict with the Dark Signers, Rua initially believed himself the fifth Signer due to his "Power Tool Dragon" resembling a dragon from Luna's vision. He advocated recruiting Akiza Izinski to aid the Signers, leading him to Arcadia Movement headquarters where he was captured and forced to duel Sayer testing for latent abilities. Summoning "Power Tool Dragon" with determination, Rua still lost and collapsed, later rescued by Bolt Tanner and Tenzen Yanagi.

When Dark Signer Devack captured Luna, Rua intervened, engaging in a shadow duel to save her. Though initially overpowered, Luna returned from the Spirit World, and together they defeated Devack, reclaiming the "Ancient Fairy Dragon" card, showcasing Rua's courage and loyalty despite not being a Signer. After the Dark Signers' defeat, he enrolled at Duel Academy with Luna and friends. Jealous of Lucciano's attention toward Luna, Rua obtained a Duel Board from Yusei to compete. When Lucciano forced Luna into a Turbo Duel, Rua joined, confronting Machine Emperor Sukiel before being defeated, knocked off a bridge, and saved by the Crimson Dragon.

In *Yu-Gi-Oh! 3D: Bonds Beyond Time*, Rua appeared during the 5D's timeline segments, arriving at Yusei's garage with Luna and Akiza. He presented archival materials about past events involving Maximillion Pegasus and Yugi Muto, assisting in identifying Paradox within a historical photograph depicting "Stardust Dragon" in an impossible era, contributing to the discovery of timeline alterations.

Later in life, Rua continued pursuing dueling ambitions. During a time skip, Crow Hogan recommended him as a replacement for a top-ranked dueling team, indicating his growth. Rua uses a Morphtronic-themed deck centered on monsters resembling household objects with effects varying by battle position. His signature card is "Power Tool Dragon," a sentient Synchro Monster capable of equipping Spell Cards directly from his deck, exhibiting traits like understanding speech and shielding him from harm during duels.