Nobuaki Kanazawa is a high school student who becomes the central protagonist of King's Game The Animation. Before the first King's Game, he was a cheerful and sociable person with many friends. That initial game, which he was the only survivor of, left him deeply traumatized and mentally scarred. He attempted to escape his past by transferring to a new school, but he carried heavy psychological damage that made him withdrawn, aggressive, and fearful of forming close bonds. He found extreme difficulty making new friends because he was terrified of losing anyone he might come to care about.

In appearance, Nobuaki has short brown hair and brown eyes, and he wears the standard Kure Academy uniform. His personality is defined by a strong sense of responsibility and a desperate need to protect others. He was the first person to try to end the King's Game by identifying the King, and he consistently attempts to encourage cooperation and trust among his classmates, even when they refuse to believe him. His earlier trauma makes him prone to flashbacks, which show how his original class quickly turned on each other under the pressure of the lethal orders. These memories fuel his resolve to prevent the same tragedy from repeating.

Nobuaki's primary motivation is to stop the King's Game and save as many lives as possible. At the start of the second game, he initially feels so overwhelmed that he contemplates breaking the rules to end his own life, but the actions of classmate Natsuko Honda force him to keep fighting. Over time, his goal evolves into a mission to avenge those who died in the first game and to bring the King to justice. He later decides to travel to the village of Yonaki to uncover the origins of the game, hoping that understanding its source will allow him to destroy it.

His key relationships shape his journey. Honda Chiemi was his girlfriend in the first King's Game; she died helping him survive, and her loss is a central part of his guilt. Naoya Hashimoto was his loyal friend who sacrificed himself in a dice-rolling order. In the new class, he forms bonds with Kenta Akamatsu, a strong and protective student who becomes an older-brother figure, and Mizuki Yukimura, a gentle girl who resists the game's demands. His most significant relationship is with Natsuko Honda, who initially appears kind but later reveals a ruthless survivalist philosophy that directly opposes Nobuaki's idealism; she becomes the main antagonist of the series. Another classmate, Nami Hirano, helps him complete a difficult order by taking her own life, deepening his trauma.

Throughout the series, Nobuaki undergoes a clear development. He starts as a broken and isolated survivor, then gradually learns to trust a small group of allies, only to face betrayal and more loss. His initial desire to die shifts into a determined will to fight and protect, even as the game's rules grow more brutal. By the end, he becomes a leader of sorts, guiding the remaining survivors in a desperate attempt to reach the truth.

Nobuaki's notable abilities come not from physical strength or special talents, but from his prior experience with the King's Game. He understands the rules and the brutal consequences of disobedience, which gives him a grim foresight that others lack. He is also surprisingly resilient, able to endure extreme emotional and physical hardship, and he possesses a strong analytical mind that helps him piece together clues about the King's identity and the game's origin. His most defining trait is his refusal to give up on the idea that people can work together to survive, even when the evidence repeatedly suggests the opposite.