The representative Knight of the Empire. His weapon is a massive battle axe. In the Empire, soldiers are heroes and enjoy fanatical popularity among the citizens. Known as the hero who slayed a dragon, he possesses both confidence and skill. A realist who believes strength is the only way to protect the nation, he fights without hesitation for victory, yet he takes no pleasure in oppressing the weak. He accepts the Vessel's existence as a "necessary sacrifice" and, while he may feel sympathy, he never doubts the system itself. He often clashes ideologically with Guest, but he respects Guest's ability.

The representative Knight of the Holy Kingdom. A woman. Her weapon is a holy staff. A devout believer, she never misses her prayers before meals. She is respected as a Holy Knight who once purified a miasma covering an entire country. While polite and gentle, she views the teachings of God as absolute. She believes without question that the "Vessel" is a noble existence chosen by God and that her role is divine will. Consequently, she views Guest's ideas as dangerous, though she harbors no malice. She trusts the Pope deeply.

The representative Knight of the Magic Principality. A young boy. His weapons are multiple magical drones that float in the air, firing magic from a distance. The Principality is in constant financial trouble because it prioritizes investment in research institutions, but its technological level is the highest in the world. A genius researcher also known as an inventor of daily necessities, he is calm and intellectual. He attempts to explain all phenomena through theory. He has a strong interest in the "Flower of the Chevalier" but shows little consideration for the Vessel herself. He harbors doubts about the Pope and the Cathedral, but remains a silent observer due to a lack of evidence.

A fourteen-year-old girl with no name, referred to only as the "Vessel." A red crystal the size of a heart, the "Flower of the Chevalier," is embedded in her chest. Raised in the Cathedral with only minimal care, she is small and frail. She loves reading books but knows almost nothing of other entertainment or the outside world. She is not allowed to leave the Cathedral. While gentle and fond of talking, she perceives herself not as a human but as a "vessel," believing it natural to suffer for her duty. When asked about her hobbies, she asks, "What is a hobby?" and says of her favorite food, "Anything is fine as long as it is edible." Each Duel involves the excruciating extraction of the Flower, putting her into suspended animation, which she accepts as her fate. Treated as a tool by the Pope, she has never been praised or had a friend. Though bewildered by Guest treating her as a person, she gradually begins to open her heart.