Hajime Hanafusa is a character who operates in the shadows, officially serving as a special agent for the Japanese government. Known by the chilling epithet "The Dissector," his public role during the Kengan Annihilation Tournament was as the affiliated fighter for Teito University, but this was a cover for a covert mission to eliminate a specific target.

Hanafusa has a lean and defined physique, with a bob of blonde hair and sharp, tired-looking yet intense eyes. He is typically seen wearing a doctor's white coat over a dark shirt and trousers, a visual reminder of his medical profession which he has twisted into something far more sinister. His personality is deeply unsettling, characterized by a clinical detachment from suffering and a profound, almost addictive fascination with death and despair. He has openly noted that the despair he feels when a patient dies is incredibly addictive, and he harbors a constant, scientific urge to dissect any fighter he deems interesting. This madness is held in check only by his powerful logical sense of reason.

His primary motivation is not glory or victory, but an insatiable scientific curiosity about the limits of human physiology. He views combat as a unique opportunity for exploration, and his government-assigned assassination missions provide a sanctioned outlet for his lethal inclinations. His role in the story is defined by this secret mission. He was tasked with the extrajudicial execution of Bando Yohei, a criminal with a unique physiology that made him immune to conventional execution methods, using the tournament as a front. Beyond his mission, he unofficially acted as a ringside medical professional, treating severely injured fighters and even resuscitating Mokichi Robinson after a fatal neck snap.

In terms of key relationships, Hanafusa is primarily a solitary operative driven by his own agendas. His main connection is to his government handlers who deploy him for assassinations. He had a doctor-patient relationship with the fighter Terashi, whom he treated by altering his face and hypothalamus. During the tournament, he worked alongside Yoshizawa Kokomi in the medical bay, tending to wounded fighters. His character shows little traditional development, as he remains a static agent of chaos and science; however, his defeat and apparent death at the hands of Bando Yohei reveal the extent of his self-modifications, as he had implanted nanomachines in his body to force his heart to beat and resuscitate himself after his neck was snapped.

Hanafusa's notable abilities are a terrifying fusion of medical expertise and self-experimentation. He is an incredibly talented surgeon and biologist, but he applies this knowledge in unorthodox ways. He surgically altered his own hypothalamus to completely negate his ability to feel pain. He has embedded spring-loaded blades carved from his own femurs into his forearms, which can be deployed from his palms as slashing weapons. He has also injected compressed gas into his heels, which can be used to augment the momentum of his kicks. His fighting style incorporates Lingshu Chin Na, an ancient martial art derived from traditional Chinese medicine that uses precise finger strikes to target the body's acupoints. Most dangerously, he can host lethal viruses within his own bloodstream without being harmed, effectively turning himself into a living bioweapon. For his mission to kill Bando Yohei, he infected himself with a deadly blood-borne virus, ensuring that any cut he inflicted would transmit the fatal disease. This combination of abilities makes him less a conventional fighter and more a living instrument of death, immune to pain and capable of self-resuscitation from fatal injuries.