Akabane Kurodo, often known by his nickname Dr. Jackal, is a primary antagonist and a recurring figure within the narrative. His past is shrouded in mystery, though it is revealed that he was once a surgeon. He served on a foreign battlefield, an experience that ended in tragedy when he failed to save a young boy's life despite his best efforts. This failure is often cited as the pivotal event that shaped his current persona, transforming a healer into someone who finds his greatest satisfaction in the opposite act. His age and exact origin are never specified, but he is known to have connections to the upper echelons of Babylon City, the mysterious towers that are central to the world's deepest secrets.

In terms of personality, Akabane is a study in unsettling contradictions. He presents himself as a consummate professional, always dressed in a long black trench coat and a wide-brimmed black hat, with a polite and soft-spoken demeanor. He often has a gentle smile on his face and uses formal language, which makes his true nature all the more jarring. Beneath this calm exterior lies a homicidal maniac who experiences battle and killing as the ultimate form of entertainment. Unlike most characters who are driven by money, revenge, or justice, Akabane's primary motivation is the pursuit of amusement. He seeks out strong opponents not out of malice, but out of a deep-seated desire to test the limits of his own power and to experience the thrill of a life-or-death struggle. He is a hedonist of violence, and his actions are guided by whatever he finds interesting at the moment. He has a habit of decapitating his enemies and sometimes carves the letter J into his victims, a calling card of his "Jackal" alias.

Akabane works as a Transporter, a person hired to deliver goods or people without asking questions. However, his role in the story transcends this job title. He serves as a formidable obstacle and a measuring stick for the main characters, Ban Mido and Ginji Amano. He first appears as an antagonist, but his role is fluid; he occasionally becomes an ally of convenience or a wild card whose allegiance is never truly fixed. His primary function is to challenge the protagonists, forcing them to push beyond their limits. He is less interested in the objective of a mission than in the battles that occur along the way. His presence signals a significant escalation in danger, as he is one of the few characters who can match or even surpass the main duo in raw power.

His key relationships are almost exclusively defined by combat. He has a deep and abiding fascination with Ban Mido, whom he views as a worthy rival. Their confrontations are cataclysmic events, with Akabane constantly seeking to force Ban into a situation where he must use his full, devastating power. He is also intensely interested in Ginji Amano, particularly the alternate personality known as Raitei, the "Thunder Emperor." After their first encounter, where Ginji defeated him by using his electromagnetic abilities to pull the metal scalpels from Akabane's body, Akabane became a persistent and terrifying presence in Ginji's life. He later replaces his metal scalpels with non-magnetic ceramic ones, demonstrating his adaptability and desire for a rematch on his own terms. Ginji is visibly terrified of Akabane, often reverting to a chibi, comedic form in his presence. Another notable relationship is with Kyoji Kagami, a rival from Babylon City. Their battles are a clash of aesthetics, with Kagami's white outfits and mirror-based powers contrasting with Akabane's black attire and blood-based abilities.

Throughout the series, Akabane undergoes a subtle but significant development. While he never loses his core love for battle, he begins to experience other emotions. In one instance, after being mortally wounded and left for dead, Ginji mourns him, asking why he had to die. When Akabane revives, simply stating he cannot imagine his own death, he asks Ginji if his survival is truly a good thing, smiling genuinely for the first time. This moment hints at a complex inner world and a potential for connection that he usually suppresses. His ultimate goal shifts from mere amusement to a search for his own limits. He desires an opponent who can show him his weakest point, a wish that is finally granted in his final confrontation with Ban. In that battle, he willingly fades from existence, satisfied to have found what he was looking for. He later reveals he survived and even helped save Ban's life by using a scalpel to suspend his vital signs, a final "favor" to express gratitude for showing him his own limits.

Akabane's abilities are both grotesque and awe-inspiring. His primary weapons are one hundred and eight surgical scalpels, which he conceals within his own body. He can summon them at will, control their trajectory telekinetically, and launch them in devastating barrages. His signature techniques are named with the prefix "Bloody," reflecting his ability to manipulate his own blood. Bloody Rain launches a torrent of scalpels into the air to rain down on an opponent. Bloody Cross allows him to bisect a target with a cross-shaped slash from a distance. For opponents he deems worthy, he manifests a Bloody Sword, a powerful blade of congealed blood that is said to be able to cut through anything, including space and dimensions. His most defining ability, however, is tied to his will. He possesses a power akin to reality rejection, where if he cannot imagine something, it cannot happen to him. Most critically, he cannot conceive of his own death, and as a result, he is effectively immortal. He has been shown to regenerate from fatal wounds and revive from death itself, simply because he refuses to acknowledge it as a possibility. This, combined with his superhuman speed, surgical precision, and a mind that treats battle as a form of art, makes him one of the most terrifying and powerful beings in his world.