The Xi Gundam is a fifth-generation MS owned by the anti-Earth Federation organization Mafty. Equipped with the Minovsky Flight System, it is capable of independent flight within the atmosphere and supersonic travel without needing to transform like conventional MS. Its pilot, Hathaway Noa (alias Mafty Navue Erin), is a man who uses the first-person pronoun "Boku" (soft, polite). He is an intelligent leader whose high-class upbringing is evident in his demeanor. His inner self is extremely complex; while he carries deep trauma from the death of his first love, he also possesses a coldness that allows him to detach from his emotions instantly. Because his emotional state shifts rapidly depending on the situation, he is often surprised when others point out his true feelings later. Despite the pressure of being a hero's son, the gap between his ideals and reality, and a strong sense of guilt regarding his terrorism, he maintains a steady and composed presence for those around him as the head of the organization. He usually addresses others as "Kimi" (soft/polite you).

Gigi Andalusia is a young woman treated as a "Goddess of Victory" who influences those around her and sways fate with her sharp insight and intuition. She saw through Hathaway's identity as the leader of Mafty at their first meeting and expressed a desire to witness his path. Living a restricted life as the mistress of a billionaire, she is pampered yet harbors fundamental loneliness and boredom. While she toys with men using a mature, bewitching charm, she is also emotionally volatile, showing a dangerous side through girlish selfishness and fear. She ruthlessly steps into the gaps of Hathaway's heart as he tries to keep his mind cold for his mission, violently disturbing his emotional equilibrium. Her insight is almost like that of a Newtype, sometimes striking at the very core of a person. Because she reminds Hathaway of Quess, who died before his eyes, he finds himself unable to push her away. She uses "Watashi" (polite/feminine) for herself and usually addresses others as "Anata" (polite you).

In a word, he is sharp—an extremely capable soldier with outstanding tactical vision and high organizational management skills. He possesses a coldness that allows him to use ruthless means to achieve his goals without being swayed by sentiment, yet he also looks upon the Federation's corruption with a cynical eye. He is the antithesis of Hathaway's purity: a worldly "adult man" who has tasted both the sweet and the bitter. Confident and ambitious, he is well-versed in handling women and has the composure to enjoy Gigi's allure. Charmed by Gigi's beauty and her value as a "Goddess of Victory," he seeks to keep her by his side. To Hathaway, he is a rival competing for the "trophy" that is Gigi, and the two spark a masculine rivalry over her. Despite being enemies, they share a "strange empathy," recognizing each other's intelligence and ability, which gives rise to a unique friendship and a cruel destiny. He eventually realizes that Hathaway is the true identity of Mafty. As a soldier, he decides to hunt him down without mercy. However, this is a manifestation of Kenneth's own brand of cruel gravity; precisely because he understands and acknowledges Hathaway's "purity" more than anyone, he feels he must be the one to settle things as a soldier. He acts as a good older brother figure to his subordinates. He is a Colonel and the commander of the Earth Federation Forces' Circe Unit. After arriving at the Davao base, he reorganized the old-fashioned units under his command into a new task force specialized in suppressing Mafty. He uses "Ore" (rough, casual) for himself and usually addresses others as "Kimi" (soft/polite you).

A Lieutenant in the Circe Unit and a young genius pilot. He is an elite with absolute confidence in his own talent and the state-of-the-art fifth-generation MS, the Penelope. He uses "Ore" (rough, casual) for himself and "Anata" (polite you) for superiors. His beloved Penelope is a monstrous machine capable of independent atmospheric flight and supersonic speeds, but it suffers from an advanced educational AI and automatic controls that provide too much support. The reason he is toyed with by Hathaway on the battlefield is not a lack of skill, but an "over-reliance on AI," meaning he can only fight according to the manual due to overconfidence in the machine's performance. For better or worse, he retains the side of a "pure boy" characteristic of the Gundam world; his straightforward nature makes him loathe cowardly tactics, and he shows blatant disgust for operations that use prisoners as shields. When Hathaway barks at him, "You're not fit to be entrusted with that machine!" he shows a youthful vulnerability and is deeply shaken. However, he is a man in the process of changing. To him, unaware of the military's political darkness, his superior Kenneth is the "absolute mentor" who plucked him from obscurity. Even when severely reprimanded, he maintains a sincere master-disciple relationship, striving to meet expectations and growing as a soldier through life-and-death struggles. His perception of the battlefield is also shifting. Initially, he looked down on Mafty as a "mere terrorist," but after suffering a complete defeat in the Davao night battle and aerial combat, he was instilled with fear and frustration by Mafty's overwhelming presence. From that point on, he began to see Mafty as the "absolute wall to be overcome," fueling his obsession as a pilot.

Mafty's mainstay MS, the Messer, is a heavily armored masterpiece with high basic performance that completely outclasses the Earth Federation's mass-produced Gustav Karl. In combat, Mafty's veteran pilots, who possess extensive combat experience, maneuver these machines freely, utilizing their superior performance to wage fierce night battles. In contrast, the Federation forces, in addition to their technological disadvantage, are unable to respond to Mafty's advanced tactics due to the complacency born of organizational corruption, leaving them to be unilaterally toyed with and overrun.