Lukather Harden, who goes by Luke, is a Makai Alchemist and former Makai Knight who operates in Russell City. He was trained in alchemy by his mother Adelaide and in knightly combat by his father Christopher. After his mother was murdered by his father, Luke abandoned his role as a Makai Knight and now works solely as an alchemist, a decision that deeply shapes his outlook and methods. He is a calm, composed, and reserved individual who speaks little and prefers to maintain a professional distance from humans, disapproving of the reckless and open-handed approach of the Makai Knight Sword, especially Sword’s willingness to involve ordinary people in the fight against Horrors. Despite his cool demeanor, Luke’s composure noticeably cracks when Sword is involved, revealing a underlying frustration and tension.

Luke’s primary motivation stems from the trauma of his mother’s death and his unresolved feelings toward his father, who resurfaces as a figure aligned with the mysterious kingdom of El Dorado. This personal conflict drives much of his character arc, forcing him to confront his past and reconsider his isolationist views. Over the course of the story, he begins to reevaluate his stance on collaboration and emotional attachment, gradually opening up to his allies.

In the group, Luke serves as the tactical and clean-up specialist. He uses a variety of firearms in battle, including an anti-materiel sniper rifle and dual pistols, all loaded with specially enchanted ammunition. One notable piece of equipment is a bullet that summons a rain capable of erasing the memories of human witnesses to Horror attacks, allowing the Makai to operate in secret. He also carries equipment that ejects wires and a bracelet designed to track Horrors. Luke is skilled enough to handle threats independently, but he eventually becomes a key member of Sword’s team, alongside the young girl Sophie and fellow alchemist Gina.

His relationships are marked by initial friction with Sword, whom he views as irresponsible, and a cautious distance from Sophie, a human child caught up in the supernatural conflict. Through shared missions and the growing threat of El Dorado, Luke learns to trust his companions and accept a more involved role. The reappearance of his father, the Makai known as Knight, forces Luke to face his deepest wounds and ultimately leads to significant personal growth. By the series’ end, he moves beyond his rigid, solitary code and embraces a more connected, protective stance toward those around him.