Keithwood is a male attendant who serves Sion Sol Sunkland, the first prince of the Kingdom of Sunkland. He excels in both literary and martial arts, making him a highly capable and professional retainer. His relationship with Sion goes back to their early childhood; the two grew up together and share a bond akin to brothers. Because of this deep history, Keithwood is one of the few people who can speak frankly and casually with the prince, often teasing him or offering dry, sarcastic observations about his behavior.

In terms of personality, Keithwood is defined by a strong sense of loyalty and devotion to his master. He is generally rational and composed, but he also has a cynical and somewhat eccentric side. He frequently serves as a voice of reason, grounding the more dramatic events around him with a practical perspective. This often translates into the role of a long-suffering straight man, as he finds himself dealing with the chaotic situations created by the actions of Mia Luna Tearmoon, the protagonist of the story. Keithwood is notably older than Sion by about four years, a gap that occasionally leads him to assume a protective, older-brother-like role, feeling a responsibility to guide the young prince.

Keithwood's primary role in the story is as a supporting character to Sion at the Saint-Noel Academy, a prestigious international school. He is constantly observant, analyzing the political and social machinations occurring among the students. A significant part of his narrative function revolves around his reaction to Princess Mia. He becomes an unwitting admirer of her supposed genius, constantly misinterpreting her self-serving and often accidental actions as parts of a grand, brilliant strategy. For example, when Mia refuses a dance invitation from Sion to partner with the less prominent Prince Abel, Keithwood interprets this as a calculated move to nurture Abels hidden talents and self-respect, rather than a chance occurrence.

This misinterpretation leads to a unique form of character development for Keithwood. Over the course of the story, he builds an elaborate and completely imaginary conception of Mia as a peerless strategist and the Great Sage of the Empire. He becomes increasingly impressed by her foresight, believing she values talent regardless of nationality or status. He eventually concludes that her true essence is a ruler who seeks to cultivate the dormant potential in every individual. This entire internal narrative is, ironically, a delusion, as the source of Mia's success is typically her desperate attempts to avoid a future on the guillotine, rather than any master plan. Nevertheless, this conviction solidifies his respect for her and leads him to privately decide that Sunkland must maintain good relations with her at all costs.

Key relationships define Keithwoods existence in the story. His bond with Sion is the most important, characterized by mutual respect, long familiarity, and genuine affection. He also develops a secondary, yet crucial, relationship with Mia, acting as a witness to her actions and a chronicler of her mythical (and mistaken) reputation. Regarding abilities, Keithwood is highly proficient with a sword, with skills that are said to be comparable to Sion, who is a prodigy. He also possesses significant culinary skills, having secretly prepared late-night snacks for Sion when they were younger, and he demonstrates practical knowledge in the kitchen.