Aaron Yuki is the only son of Kai and Reina Reid and the twin brother of Carey. He is the younger cousin of Katie and Kylie and Jaden's children. In terms of appearance, he takes after both his parents, having his mother's brown hair but with black streaks and her mother's amber-brown eyes. Like his mother and sister, he can see Duel Spirits with his being Gem-Knight Topaz, which shows that he duels with his mother's "Gem-Knight" Deck.
Aaron was born in the same hospital as Cody Anderson and at the same time as him.