Keough, also known as Haze, is a supporting character from the anime and the elder brother of Yufa, one of the main heroines. He is a knight by class and hails from the Norman race. His background is defined by a tragic incident that sets the course for his involvement in the story. Keough was a childhood friend of the warrior Iruga and accompanied him on an expedition to investigate the dangerous ruins of Glastheim. During this mission, the group was forced to flee, but their escape was blocked by a powerful Abysmal Knight. In a moment of self-sacrifice, Keough ignored Iruga's protests and distracted the creature to allow Iruga, Roan, and his sister Yufa to escape. Before anyone could return for him, Keough was fatally stabbed, and the doors to the ruins closed, leading everyone to believe he had died.

In reality, Keough did not die but was instead brainwashed and corrupted by the Dark Lord, the primary antagonist of the series. His stab wound was inflicted by a weapon known as the Blade Lost in Darkness, a symbolic injury that foreshadowed his transformation into a servant of evil. After his corruption, he was given the nickname Haze by Iruga. As a subordinate of the Dark Lord, Keough's primary motivation is to serve his master's agenda, specifically to lure his sister Yufa to the dark side. Yufa possesses a soul crystal, one of the seven crucial items needed for the Dark Lord's full revival. By using Keough, a figure Yufa deeply loves and mourns, the Dark Lord aims to manipulate her emotions and claim the crystal.

In the story, Keough acts as a tragic antagonist. His role forces the main characters, particularly Yufa and Iruga, to confront a past they cannot escape. His presence creates intense emotional conflict for Yufa, who must decide between saving her corrupted brother or stopping the Dark Lord's plans. For Iruga, Keough represents a failed promise and a friend he is desperate to redeem. Key relationships define his arc: his bond with his sister Yufa is the primary tool for his manipulation, his friendship with Iruga represents a connection to his former heroic self, and his role as a minion to the Dark Lord shows his complete subjugation. Despite his corruption, his original personality briefly resurfaces at the moment of his death. Mere seconds before dying, he reforms, apologizes to Iruga for everything he has done under the Dark Lord's control, and finds a measure of peace.

Keough's development is one of tragedy and brief redemption. He begins as a heroic knight who sacrifices himself for his friends, is transformed into a brainwashed pawn of evil, and finally breaks free from that control just before his ultimate demise. Even after his physical death, his influence continues. His soul appears to Yufa in a dream, advising her not to repeat his mistakes and telling her to trust and follow Roan, who will protect her. This final act of guidance helps free Yufa from the Dark Lord's own corruption later in the series. In terms of notable abilities, as a knight, Keough is a skilled warrior. After his transformation, his abilities are augmented by the dark powers granted by the Dark Lord, but he is ultimately still a subordinate whose fate is controlled by his master. The Dark Lord himself eventually kills Keough during the final battle to claim the soul crystal from him.