Leo

Luka, known in Japan as Rua or Lua (see below), along with his twin sister Luna, aid Yusei Fudo, whom they adore and support in his duels while making fun of fate. Rua is the older twin of the two and has a lively and blundering personality, being easily irritated by his sister's insults.

Character design
Luka's outfit is similar to his sister's; it consists of a short-sleeved light blue jacket over a sleeveless dark blue shirt with golden markings that differ from Luna's shirt. He also wears light blue shorts with a dark blue belt and blue sneakers of the same color. Luka also has a bracelet on each wrist and his blue-green hair is pulled into a single, high ponytail with two shoulder-length bangs on both sides of his face. He carries a Duel Disk with a blue and white trim on his left, which was originally too big to fit until Yusei remodified it.

Character biography
Luka lives together with Luna in the Tops residental area. They spend most of their time alone together as their parents are usually at work. They are educated via the Internet, so they spend most of their time inside.

Luna was able to sense Yusei when he was shocked by the police officers so she and Rua rescue him after his duel with Ushio and take him to their home. Yusei wanted to leave, fearing he may place them in danger, but Luka talks him into a Duel. After Yusei wins, they manage to get him to stay for the night.

Luka and Luna awaken the next morning to find that Yusei had left after modifying their Duel Disks to fit their small arms. Luka then leaves with Tenpei to find and duel the Black Rose Witch. They eventually meet up with Yusei again and shortly afterward the Witch appears, but leaves after seeing Yusei's Dragon's Birthmark, which seemingly to disgust her. Luka seems to show fear for both the Witch and the Birthmark.

Luna was selected as someone to participate in the Fortune Cup, but she didn't feel like participating, so Luka planned to disguise himself as her and compete instead. The next day, Luka enters the Fortune Cup in disguise as Luna, but quickly loses to Bommer after a hard-fought duel. Using Akutsu's Signer-detecting technology, Jeager determines that Bommer dueled Luka instead of Luna. During the consolation duel where Luna dueled Professor Frank, Luka was hypnotized along with his sister and later reveals to her that he had unconsciously given himself the task of protecting her while she protects the Duel Spirits' Dimension. He was awakened from his trance when the duel ended.

At the end of the first day of the Fortune Cup, it is shown that Yusei would be paired against Bommer the next day. As Himuro wondered what kind of Duel Runner he has, Luka tried to see what kind he had and ran off. He was scared away by Bommer's Duel Runner.

Naming


Linework by Kazuki Takahashi has revealed the Japanese names of Luka and Luna to be Rua and Ruka. A possible misinterpation of the writers of the anime, due to common confusion between "L" and "R" has revealed the Japanese names to be Lua and Luca

Deck
Luka plays a Morphtronic Deck that features an Archetype of monsters known as "Morphtronics" whose effects are dictated by battle position. The monsters' appearances are derived from various objects such as cell phones, lighters, and magnets.

In the second ending, he is shown to have a robotic Dragon monster that may or not be one of the five dragons