Koyo Hibiki (響紅葉, Hibiki Kōyō) is the younger brother of Midori and a three-time Duel Monsters world champion. Koyo was a great Pro League Duelist who used "Elemental Heroes" and is the former owner of the "Elemental Hero" Deck used by Jaden in the series proper as well as the owner of "Winged Kuriboh."