Guy Greenwood is a main character who attends Kimberly Magic Academy, where he quickly becomes a founding member of a close-knit group of friends known as the Sword Roses. He comes from a line of magical farmers, a background that deeply influences both his personality and his unique magical abilities, marking him as someone connected to the land and nature rather than aristocratic magical lineage.

In terms of appearance, Guy is notably the tallest of the main friend group, with a broad-shouldered and sturdy build. He has short auburn hair and light brown eyes, and his standard school uniform is worn without much customization, though he notably chooses not to wear the regulation necktie.

Guy’s personality is cheerful, friendly, and easygoing. He is described as a frank and pleasant individual who does not feel the need to put on airs, behaving in many ways like a typical country boy who simply wants to get along with others. Despite his casual and relaxed demeanor, he possesses a strong sense of politeness and thoughtfulness, showing genuine concern for the well-being of his friends. He is fiercely loyal; when his companions are insulted or threatened, his usual smile disappears, and he is immediately ready to defend them, even if it means jumping into a physical altercation. While he is generally positive and warm, he can become serious and focused when the situation demands responsibility. This balance of lightheartedness and a strong sense of duty makes him a reliable and stabilizing presence within the group, often acting as an emotional anchor who lightens tense moments and strengthens group cohesion through empathy.

Within the story, Guy’s primary role is as the heart of the Sword Roses. He is not always at the center of combat but consistently proves his value through support, creative strategies, and magical utility. His unique talent lies in his mastery of magical flora, often described as a "green thumb" for magical plants. He grows unique varieties of plants that can be used in a range of unusual and helpful situations. On the battlefield, he uses terrain manipulation and plant-based magic for defensive and supportive purposes, preferring these strategies over purely aggressive combat. He also knows offensive magic, such as the spell Tonitrus, which unleashes bolts of electricity.

Guy’s key relationships define much of his role in the group. He shares a deep, platonic bond with his fellow Sword Rose, Katie Aalto. While they get along well, they also have a slight rivalry, particularly concerning cooking, as they often compete to see whose dishes are more popular among their friends. As two of the less combat-focused members of the group, Guy and Katie sometimes find themselves left behind to "hold down the fort" during major battles. He also has a strong friendship with Oliver Horn, respecting Oliver’s leadership and strength while also providing balance to Oliver’s more serious nature. Guy is one of the few who can call Oliver out without causing conflict, and their friendship is built on mutual trust and shared ideals. He has an underclassman, Rita Appleton, whom he has taken under his wing as an assistant in his academic research; she is noted to have a crush on him.

Guy undergoes significant development as the series progresses. In a later volume of the light novel series, he awakens as a "curse wrangler," a development that temporarily separates him from the Sword Roses. This event deeply affects the entire friend group, straining their dynamic but also providing a major opportunity for character growth as they all begin to think more seriously about their futures and the paths their magecraft will take.