Kieffrey is a witch who runs his own atelier and serves as the teacher and guardian to four young apprentices, including the story's main character, Coco. He is a former disciple of the Sage Beldaruit, having been rescued and taken under his wing after a tragic incident in his childhood.

Physically, Kieffrey is a tall, slender young man with white hair and blue eyes. His most notable feature is that he is missing his right eye, a loss he conceals behind a pair of small glasses where the right lens is dark and the left is clear. He typically wears white robes and a pointed cap, presenting an appearance that is both striking and somewhat enigmatic.

Kieffrey's personality is characterized by a profound duality. On the surface, he is a patient, kind, and supportive teacher who deeply cares for the well-being and individual growth of his students. He encourages them to explore their unique talents and is fiercely protective of them, even when it means defying authorities such as the Knights Moralis. He communicates with a poetic and whimsical manner of speaking that sets him apart from other characters, especially during serious or sad moments.

Beneath this gentle exterior, however, Kieffrey harbors a deep-seated and consuming obsession. He is driven by a hidden hatred for a group known as the Brimmed Caps. This quest for revenge and answers forms the darker core of his personality, causing his otherwise calm demeanor to be replaced by a relentless and sometimes reckless fury whenever he confronts them or pursues a lead on their activities.

The source of his trauma and motivation is a childhood incident in which he was captured by the Brimmed Caps. They erased his memories, took his right eye, and sealed him inside a water-filled coffin, burying him alive to die. He was eventually found and rescued by the Knights Moralis and Sage Beldaruit. The experience left him with a fear of water and an unyielding resolve to find the witch who took his memories and restore what was lost to him.

This past trauma heavily influences his role in the story. His primary motivation for taking on Coco, an outsider who accidentally turned her own mother to stone with forbidden magic, is not purely altruistic. He sees her as a direct link to the Brimmed Caps, who show a suspicious interest in her, making her a valuable lead in his pursuit of them. His quest for vengeance is so consuming that he is willing to act against his own best interests and his relationships. In a notable instance, he confessed his true plans to his childhood best friend and housemate, Olruggio, only to erase Olruggio's memory of the conversation to protect his secret.

Kieffrey shares a long and deep friendship with Olruggio, who acts as a watchful eye over the atelier. Their relationship is one of the most significant in his life, providing a foundation of trust that Kieffrey nonetheless betrays in his obsession. As a teacher, he has a complex dynamic with his apprentices: Coco, who is unknowingly at the center of his revenge plot; as well as Tetia, Richeh, and Agott, each of whom he has taken in from difficult circumstances. As the story progresses, his dark past and ulterior motives come to light, creating tension and forcing those around him to reconcile the caring mentor they know with the obsessed man he truly is.

In terms of abilities, Kieffrey is a highly talented and creative witch who specializes in water magic. He is known for his craftiness and intelligence, having invented various magical contraptions and unique spells, including his signature water illusions. He uses his knowledge not only for his own purposes but also to provide insightful guidance to his apprentices, helping them develop their skills and understand complex magical principles.