Sam Son begins as a British soldier subjected to the "Human Weaponization Concept" codenamed Rabbit. This experimental project transforms him, inducing red eyes and heightened aggression when enraged. Following the death of his comrade Charlie, another Rabbit test subject, Sam Son becomes driven by personal pride and a warrior's ethos to avenge Charlie's defeat. This quest for vengeance leads him to join Klaus Daggats' forces at the Spiral Palace in Grazia.

A disciplined Muay Thai fighter, Sam Son's combat style reflects his background. He does not fight under coercion or direct orders for Klaus Daggats; his actions stem solely from his own sense of honor and commitment to proving his strength. His primary conflict erupts when he confronts Taito Masaki, whom he perceives as responsible for Charlie's defeat and the rightful target for his vengeance. Their decisive clash occurs within a dilapidated mini-coliseum inside the Spiral Palace.