Fujio is one of the two main protagonists in the story, originally a worker at a fire extinguisher factory located near the outskirts of Tokyo. He is visually defined by his large, distinctive afro hairstyle and is often seen wearing an orange uniform or similar work clothes, which contributes to his everyman appearance. In terms of background, Fujio is presented as a slacker and a somewhat slow-witted individual who prefers to spend his time practicing martial arts rather than focusing on his mundane job. He is a student of Brazilian jiu-jitsu, a grappling-based combat sport he learns from his friend and coworker, Mitsuo.

As a character, Fujio is defined by a combination of dim-wittedness and a quick, often uncontrollable temper. While he is generally portrayed as a bumbling everyman, his impulsive nature can lead to sudden and extreme violence when he or someone he cares about is threatened. A core element of his personality is his deep-seated trauma from a childhood experience, as he repeatedly suffers flashbacks to being sexually abused by a former teacher. This trauma acts as a significant psychological trigger, making him particularly susceptible to manipulation by those who know about it and can be used to unleash his hidden rage. Despite his violent outbursts, the narrative frames him as a figure of absurdist comedy, and his devotion to his friends and later his family reveals a more earnest, if flawed, loyalty.

Fujio's motivations evolve over the course of the story. In the beginning, his primary goal is a simple one: survival. His accidental murder of their abusive boss—striking him with a fire extinguisher—forces him and Mitsuo to flee the city as a zombie outbreak begins. This event initiates their journey. Later, after a five-year time jump, society has collapsed into a rigid class system where the wealthy elite enslave the poor in a walled-off section of Tokyo. In this new world, Fujio is motivated by the desire to protect his new family, consisting of his partner Yoko and their young daughter. He participates in organized zombie fights, a brutal form of entertainment for the rich, hoping to improve their living conditions.

Regarding his role in the story, Fujio serves as the central figure who links the two distinct halves of the narrative. The first half follows his slapstick escape from the initial zombie hordes, while the second half sees him as a seasoned zombie wrestler in a dystopian society. His most significant relationship is with his friend and jiu-jitsu mentor, Mitsuo. The two share a deep bond, though their dynamic is often characterized by misunderstanding and Fujio's reliance on Mitsuo's guidance. When Mitsuo believes he has been bitten and becomes a zombie, Fujio continues his legacy by using their martial art in the fighting pits. Their relationship reaches a climax when Fujio is forced to confront Mitsuo, who has become a legendary fighter in the zombie arena. Another key relationship is with Yoko, a woman he rescues early in the apocalypse. Their relationship is depicted as a bickering but ultimately affectionate partnership, and by the end of the story, they have a family together.

Over the course of the narrative, Fujio develops from a simple, lazy student into a reluctant but capable fighter and family man. While he never loses his intellectual slowness, he gains a sense of responsibility. His jiu-jitsu skills, which were once a hobby, become his primary tool for survival and his profession in the zombie arena. This skill set is his most notable ability; he uses Brazilian jiu-jitsu to efficiently dispatch the undead, often ending fights with a single, practical move. This efficiency, while effective, is noted for being boring to watch, which creates conflict with the spectators who crave more violent and spectacular shows. Ultimately, his journey is one of accidental heroism, driven by circumstance, friendship, and a stubborn will to live.