Asatoo Ichijou is a significant figure in the world of aristocratic vampires, primarily recognized as the grandfather of Takuma Ichijou and the formidable head of the Vampire Council. Often referred to by the title Ichio, he is the leader of one of the most distinguished and influential clans, having expanded the Ichijo Group's reach so pervasively that its influence extends even into human business transactions. His advanced age is contrasted by an appearance that seems to be that of a man in his forties, with pale blonde hair similar to his grandson's and striking icy blue eyes.

In his role as the head of the Vampire Council, Ichijou holds a position of immense power and authority over vampire society, a role he takes very seriously. His personality is marked by a cold and calculating demeanor that inspires fear in many other vampires. This outward cruelty, however, is tempered by a genuine, if understated, concern for his grandson, Takuma, for whom he had planned a future as his successor within the Council. Ichijou harbors a deep and intense dislike for Pureblood vampires, a sentiment born not of simple prejudice but of a profound fear of the immense and uncontrollable power they wield over all other vampires. He views their very existence as a fundamental threat to the established order of vampire society.

This fear and distrust of Purebloods directly shapes his motivations and his actions concerning Kaname Kuran. Following the death of Kaname's parents, Ichijou sought to become the young Pureblood's guardian, an offer that Kaname ultimately refused. This refusal did not deter Ichijou; instead, he adopted a strategy of surveillance and control. He permitted his grandson, Takuma, to attend Cross Academy with the specific mission of spying on Kaname, monitoring his activities from within the institution. Ichijou's ultimate goal was to supplant Kaname with another Pureblood, Rido Kuran, believing that Rido would be a more pliable figurehead, allowing the Council to exert greater control. He became entangled in the阴谋, or conspiracy, led by Rido, supporting the idea that Rido should replace Kaname as the head of the Kuran family. His secret hope was to see the Purebloods destroy one another, thereby eliminating what he saw as the greatest threat to vampire order.

His relationships are central to his role in the story. With his grandson Takuma, the dynamic is a complex mix of familial expectation and political maneuvering. While he wished for Takuma to inherit his position, he also unhesitatingly used him as a tool to monitor Kaname. This creates a deep conflict, as Takuma values his friendship with Kaname and does not wish to betray him. Regarding Kaname, Ichijou maintains a veneer of respect, addressing him with the honorific "Kaname-sama," but his actions reveal a deep-seated hostility and a relentless campaign to undermine and control him.

Ichijou's secret dealings extended to collaborating with the president of the Hunter's Association, an alliance that demonstrated his willingness to use any means to achieve his political ends. As a high-ranking aristocratic vampire, or Level B, Ichijou possesses the standard abilities of his kind, including slow aging and regenerative healing powers. He also demonstrated a capacity for lethal physical force, effortlessly twisting the neck of a former head of the Hunter's Association. His development culminates in a confrontation with Kaname, where he reveals his knowledge that Kaname is one of the original vampire ancestors and declares his belief that his own actions, however ruthless, were justified. Before their conflict can conclude, his grandson Takuma intervenes, rejecting Ichijou's philosophy that the ends justify the means, and ultimately kills him.