Eric Brooks, known to the vampire underworld as Blade, is a Daywalker, a unique hybrid born from a human mother who was bitten by a vampire during childbirth. This traumatic origin granted him all the superhuman strengths of a vampire without their primary weaknesses, such as an aversion to sunlight, though it also cursed him with an unending thirst for blood. He was born in Soho, London, and his early life was marked by tragedy. His surrogate family was ultimately killed by his own mother, who had not perished from the vampire attack as he had believed, but had been turned into a vampire herself. Using a silver knife, a young Eric was forced to destroy her.

This formative event forged his path as a hunter. To control his vampiric urges and hone his skills, he was taken in by the seasoned vampire hunter Noah Van Helsing, who provided him with a specialized serum to suppress his bloodlust and trained him in the tactics and combat required to kill vampires. Seeking to master his weapon of choice, Blade later traveled to Japan to study swordsmanship under the master instructor Tanba Yagyu. During this period, he developed a fierce rivalry with a fellow student, Kikyo Mikage, whom he bested in a duel upon his departure, demonstrating not only his skill but also a cold, pragmatic sense of mercy by refusing to deliver a killing blow.

Blade's personality is defined by his grim, driven, and solitary nature. He is a man on a focused mission to eradicate the monsters that plague humanity, an obsession born from personal loss. As he states himself, he hunts the creatures that prowl the night, and the vampires have come to fear him, dubbing him Blade. His primary motivation is his quest for vengeance against the four-fanged vampire, Deacon Frost, the ancient and powerful pureblood who murdered his mother and is responsible for his cursed existence. This mission leads him to investigate and dismantle Existence, a global organization run by Frost that uses nightclubs and a network of human familiars to lure prey and consolidate power.

In the narrative of the anime, Blade operates as a lone agent but forges key relationships that influence his journey. His mentor, Noah Van Helsing, serves as a father figure and logistical support, providing the serum that keeps his monstrous side at bay. His training in Japan connects him to Tanba Yagyu, a master whose teachings are integral to Blade's combat style. The rivalry with Kikyo Mikage evolves into a complex dynamic, as Kikyo represents a path Blade rejected, and their past haunts their future encounters. Blade also crosses paths with Makoto, a young woman who also hunts vampires, and while he typically works alone, their objectives temporarily align. A significant element of his development is his confrontation with the past, most poignantly seen when his former master, Tanba Yagyu, is turned into a vampire by Deacon Frost. Blade is forced to destroy his own teacher, a tragic event that underscores the personal cost of his war and demonstrates his resolve to end the suffering of those corrupted by vampirism, offering his master a final, merciful release. After achieving his primary goal of killing Deacon Frost and destroying Existence, Blade decides to continue his duties, protecting humanity from the vampire threat.

As a Daywalker, Blade possesses a formidable array of abilities. He has the superhuman strength, speed, agility, and endurance of a vampire, along with accelerated healing and a greatly extended lifespan. Crucially, he lacks their weakness to sunlight, allowing him to hunt during the day. However, he must constantly struggle against his own bloodthirst, which he manages with the serum developed by Van Helsing. His combat skills are exceptional, making him a master tactician and weapon handler. He is a highly proficient marksman and employs an arsenal of specialized weaponry designed to exploit vampiric weaknesses. His most notable ability is his mastery of Yagyu Shinkage-ryu, a kenjutsu art that transcends normal swordsmanship. This style allows him to unleash powerful shockwaves or invisible wind blades from his sword swings. It also grants him access to three principal techniques: The First Blade, Residual Moon, which creates a tangible after-image of himself to confuse opponents; The Second Blade, Phantom Moon, a high-speed spinning slash so intense it sets the air ablaze; and The Third Blade, Chaotic Moon, which launches several shadow blades around the enemy, concealing the true path of the user's attack.