Herman Lewis is a central character and the father of the protagonist, Leon Lewis. He is a Makai Knight who holds the title of Zoro the Shadow Cutting Knight, also referred to as the Knight of Darkness. Before the events of the story, he originally went by the name Roberto. His past is marked by tragedy during a kingdom-wide witch hunt in Valiante, where he and his wife, the Makai alchemist Anna, were imprisoned for witchcraft. Herman managed to escape his cell but arrived too late to save Anna, who was burned at the stake. However, he was able to rescue their newborn son, Leon, who was protected from the flames by his mother’s magic. Following this, Herman fled the kingdom and raised Leon in exile, training him as a Makai Knight while evading the forces of Valiante.

Herman is characterized by a personality that is outwardly irresponsible, uninhibited, and lecherous. He frequently indulges in the company of women and is often seen in compromising situations, which leads his son to view him with a lack of trust and considerable irritation. He defends this womanizing behavior by claiming that he needs to father another son, as Leon has inherited the Golden Armor, Garo, from his mother and cannot take on Herman’s own title. He thus seeks a successor to carry his own armor, Zoro. Despite these annoying antics, he is also very perceptive, bold, and a highly skilled knight. When the situation demands it, he becomes entirely serious and capable, expertly reining in his son’s reckless tendencies and getting the job done. Beneath his cavalier surface, he holds deep love for Leon, tolerating the boy’s bitter disposition and physical abuse as a result of his own behavior out of paternal affection.

In the story, Herman’s primary motivation is to raise Leon into a fine Makai Knight and to eventually find an heir for his own armor. He plays a crucial role as a mentor and foil to his son, sometimes acting irresponsibly to give Leon an example of what not to do, while always keeping a watchful eye on his safety. As the plot progresses, Herman is ordered by the Watchdog to cooperate with the chief adviser Mendoza as part of a plan to thwart the villain’s schemes from within. This forces him to take a hostile stance against Leon and his allies, though his true intent is to stop Mendoza. After a severe injury in battle, he is cared for by an innkeeper named Ximena Colorado. He later dies during a final assault by a horde of Horrors, and his soul is absorbed into a crystal. His legacy continues through Ximena, who bears his second son, Roberto, and it is revealed that Herman wished for her well-being in his final moments.

Herman undergoes significant development, initially appearing as a purely lecherous deadbeat. However, his true nature as a serious, loving, and self-sacrificing father is gradually revealed. In the film Garo: Divine Flame, he is temporarily resurrected by a priest in an unstable, Horror-like state where he risks turning into a monster. Even in this condition, his primary concern is protecting his new family, Ximena and Roberto, and he ultimately defends them by sacrificing himself once more.

As a Makai Knight, Herman possesses notable abilities. He is an incredibly skilled combatant, having defeated the fallen knight Bernardo in single combat. In battle, he wields two specialized daggers that transform into curved short swords when he dons his silver Zoro armor. These blades are attached to his wrists by long chains wrapped around reels, allowing him to extend them for long-range attacks or to entangle enemies. The two swords can also be combined into a larger, spade-like blade or detached and joined at the hilts to form a boomerang-like weapon. His armor is noted for its asymmetrical design and silver coloring, similar to the Knight Zero from the live-action series, and he rides a Makai Horse named Getsuei. He is also partnered with a magic tool called Zirva, which takes the form of a bracelet.