Justice is the primary antagonist of the story and holds the position of the Number One for most of the first season. His physical appearance is distinct and anachronistic, as he dresses in traditional cowboy garb consisting of a large poncho, a wide-brimmed cowboy hat, and boots while wielding two long-barreled revolvers. He is also a smoker. His most defining physical trait is his diseased-looking skin, marked with various blotches and discolorations. This condition, along with his possession of a third arm hidden on his back, is implied to be the result of a past accident, possibly involving submersion in toxic waste.

In terms of background, Justice was originally the Number Two who arrived at Mount Shumi to challenge Afro's father, Rokutaro, for the Number One headband. The duel was fierce but short, ending with Justice decapitating Rokutaro using the hidden sword in his third arm. After claiming the Number One headband, he callously discarded his opponent's severed head in front of the young Afro, telling the grief-stricken boy that the moment would haunt him forever and to challenge him when he was ready to duel a god.

Justice's motivations are rooted in a grand, brutal philosophy for ending the Headband Wars and bringing peace to the world. He believed that absolute peace could only be achieved through absolute power, a view that directly conflicted with Rokutaro's belief in simply hiding the headbands. Justice originally thought that possessing the Number One headband alone would grant him the power of a god. However, in the years that followed while Afro grew up, Justice came to believe that ultimate power required owning every headband, not just the top one. This revelation led him to systematically kill all the other numbered headband holders, whose corpses are displayed in his throne room.

His personality is cold, ruthless, and power-hungry, driven by a messianic delusion of becoming a god to rule the world and end all conflict by force. He is also highly strategic and calculating, relying on tricks like his concealed third arm to deceive opponents. Despite his maniacal laughter and thrill-seeking nature, Justice is portrayed as a figure who believes his own horrific actions serve a higher, noble purpose of creating order out of chaos.

Justice's role in the story is singular: he is the ultimate target of Afro Samurai's single-minded quest for vengeance. He is the murderer of Afro's father and the catalyst for Afro's entire journey. Their key relationship is that of hunter and hunted, though Justice is fully aware of this dynamic and has been waiting for Afro to mature into a worthy opponent. Within the narrative, he serves as the final obstacle for Afro to overcome.

His development takes an unexpected turn in the sequel, Afro Samurai: Resurrection. Though he was seemingly destroyed by Afro at the end of the first season, he appears to have survived. He makes several small cameos, such as a statue head and as part of a hallucination, before being revealed at the very end of the film. There, he is shown fully healed and meeting with a mysterious masked man named Takimoto, who comments that he has been waiting for him for a long time, hinting at a continued role in the world.

Justice possesses several notable abilities that make him an extraordinarily dangerous foe. He is an exceptionally skilled gunslinger capable of wielding his two revolvers with deadly speed and accuracy. His most infamous trait is his hidden third arm, longer and more twisted than his normal limbs, which he uses to wield a katana for a lethal surprise attack. This earned him the nickname the Three Armed Gunman. Justice also displays a horrifying degree of vitality, capable of surviving near-decapitation. He can enter a withered, mummified state and regenerate his youth and physical prowess by absorbing blood. Furthermore, he seems able to manipulate the environment of his throne room, most notably generating a large spike from the ground to impale his opponents.