Mr. Kay, also referred to as Mr. K, is a minor character in the anime Yu-Gi-Oh! Zexal. In the original Japanese version his name is Ukyo Kitano. He serves as the homeroom teacher of Yuma Tsukumo and his classmates at Heartland Academy. He has wavy brown hair, green eyes, and typically wears a pink collared shirt under a brown vest with matching brown pants. His outwardly cheerful and well-meaning personality reflects his genuine desire to bring joy to those around him. However, Mr. Kay becomes a temporary antagonist when he is possessed by the Number card Number 34: Terror-Byte, which corrupts his intentions and forces him to duel against Yuma. Under this influence he displays a more aggressive and calculating demeanor, using his considerable computer knowledge to create viruses and manipulate technology. His motivations prior to possession are simply to be a supportive teacher, and after he is freed from the Number’s control he returns to his normal, kind-hearted self with no lasting antagonistic role. Mr. Kay’s key relationship is with Yuma Tsukumo, whom he instructs at school and later duels as an opponent when possessed. He also interacts with other students, but he does not form close bonds with the main cast beyond his classroom duties. His character development is limited, as he appears only in a handful of episodes and does not undergo significant personal growth; his primary arc involves being rescued from the Number’s influence. In terms of abilities, Mr. Kay is a proficient hacker capable of writing computer viruses and sabotaging electronic systems, and he uses a Crash Bug Deck in duels, which focuses on Insect-type monsters and strategies involving inflicting damage through virus-like effects. When possessed by Number 34: Terror-Byte, he gains the ability to use that card, a Rank 3 Xyz Monster that can steal the effects of an opponent’s monster as its own. Mr. Kay’s role in the story is that of a minor obstacle and a demonstration of the threat that Numbers cards can pose even to ordinary people.