Kazuo Fujisawa is a character who serves as the first opponent for the protagonist, Nao Kanzaki, in the Liar Game tournament. His past is directly tied to Nao's, as he was her homeroom teacher during her middle school years. In that capacity, he presented himself as a caring and compassionate figure, notably offering her genuine support and advice when she confided in him about her father's illness and her anxieties regarding the future. This established a relationship of trust and fond memory for Nao, making their eventual reunion in the game particularly significant.

Beneath this formerly kind exterior, however, Fujisawa harbors a deeply different personality shaped by his unfortunate life experiences. After being fired from his teaching job, he remained unemployed for a long period, a situation that led his wife to divorce him and take their child. This chain of events left him bitter, cynical, and consumed by a desperate need for financial security. While he initially maintains a friendly and helpful demeanor upon meeting Nao again, this facade quickly crumbles to reveal a greedy, selfish, and manipulative individual. He is willing to lie and cheat without remorse, even targeting a former student who trusted him, and he mocks her for her honesty, suggesting that such trusting people cannot survive in the world. His motivation is overwhelmingly driven by his debt and his belief that he needs the money far more than anyone else, caring more about his own wealth than the well-being of others.

In the story, Fujisawa acts as the initial antagonist, embodying the deceitful and cutthroat nature of the Liar Game. His role is to be the first obstacle that forces Nao to confront the game's reality, ultimately leading her to seek the help of the genius swindler Shinichi Akiyama. The central relationship is, of course, with his former student, Nao Kanzaki. He exploits her trust in him as a respected teacher to steal her one hundred million yen, setting the stage for the entire first round of the game. This act transforms their relationship from one of mentor and student to that of a predator and his prey, though Nao’s inherent compassion later challenges this dynamic.

Fujisawa undergoes a notable, if limited, development throughout his time in the story. Initially confident and gloating over his successful deception, he becomes increasingly paranoid and unravels psychologically as Akiyama applies pressure. He becomes a nervous wreck, confining himself to a single room in his house for days, barely sleeping, and growing ever more desperate to protect his stolen fortune. His paranoia, which was first his tool for preemptively stealing from Nao, becomes his fatal flaw. After his inevitable defeat, he is left in a state of despair, facing a tremendous debt. However, in a moment of profound kindness, Nao uses her winnings to pay off his debt. This act of forgiveness reduces him to tears of gratitude and shame, suggesting a potential, if ambiguous, moment of remorse for his actions.

Fujisawa's notable abilities are not physical but psychological. He is a skilled and convincing liar, capable of maintaining a kind facade while executing a calculated betrayal. He is also shown to be cunning and prepared, going to extreme lengths to protect his money, such as securing his cash in a heavy safe, chaining it to the wall, and even fashioning improvised armor for himself. Despite these efforts, his strategic thinking is ultimately no match for the superior intellect of Shinichi Akiyama, who outmaneuvers him through a sophisticated bluff and a disguise.