Koyo Hibiki is the younger brother of Midori and once a three-time Duel Monsters champion. Koyo was a great Pro League Duelist who used Elemental Heroes. Chazz received an autograph from him, and in the process, Kouyou's "Winged Kuriboh" altered Chazz's "Light and Darkness Dragon" card. However after losing a Shadow Game to a mysterious duelist, he found that every time he drew a card while dueling seriously, the deck of his heart would be depleted, at which point he would die. Kouyou suffered from this and was sent to the hospital where he met a young Jaden who had broken his leg while playing baseball. He taught Jaden all he knew about dueling and to always have fun dueling no matter what. With his health failing, he decided to give up pro-dueling and made Jaden his final opponent. After defeating Jaden, he gave him his deck and his lucky red jacket. However, he found that in this he had drawn the last card, completing the curse and falling into a permanent coma, presumably dying.
Koyo's full name means "autumn colors".
Deck
Koyo plays an nature-based Elemental Hero Deck. Before the start of the manga, Koyo gave Jaden his deck, including the one-of-a-kind "Elemental Hero Terra Firma" card.
