Armstrong Ozuma stands as Hyūma Hoshi's prominent rival, hailing from a wealthy family. His complex relationship with his father fuels a fierce competitive streak and an intense drive for athletic recognition, channeled entirely into baseball. On the field, Ozuma radiates pride and dynamism, deliberately contrasting Hyūma's emphasis on fair play and sportsmanship. This rivalry escalates into professional baseball, where Ozuma emerges as a key opponent for Hyūma, notably in clashes against the Hanshin Tigers.

Ozuma exhibits unwavering determination to win at all costs, yet beneath his dominant exterior lies loyalty and care toward family and teammates, adding depth to his persona. His profound commitment to baseball drives him to employ rigorous training methods, developing advanced pitching techniques specifically to challenge Hyūma.

His pitching style evolves continuously throughout the series, incorporating increasingly sophisticated and strategic approaches termed "magical pitching techniques" during their high-stakes matchups. This progression cements his role as a persistent, ever-adapting adversary.

Ozuma's character design draws inspiration from Major League Baseball icons Lou Brock and Bob Gibson, embodying traits of power and speed that position him as a formidable talent within the series. He maintains a consistent presence across the franchise, appearing in the original television series and films like "Kyojin no Hoshi: Shukumei no Taiketsu," with his competitive dynamic against Hyūma remaining central to his narrative function.