A lightning-quick gun-fighter and current #1 fighter of the world, little is known of this reclusive warrior. The only thing known for sure is that he killed the prior top fighter in the world in a one-on-one duel -- that top fighter was the father of Afro Samurai. It is rumored that his strange skin color is due to some kind of horrible accident.

The holder of the Number One headband for most of season one, Justice is the man who killed Afro's father before his eyes many years ago and to some extent convince him to challenge him when he was old enough. He is a remarkably skilled gunman, dressing in a cowboy garb with the Number One headband tied around his wide-brimmed hat. He has discolored, diseased-looking skin, which his bio on the official site implies is the result of a past accident (undecided, but assumed by the publishers to have been submerged in toxic waste) which would explain his abnormal abilities. Justice has the ability to regenerate himself after being exposed to blood, as seen just before his final fight with Afro when the injured hero's blood flows to Justice's feet and his withered body begins to reshape into the young version that fought Afro's father. He also has a third arm hidden on his back that holds a sword for catching opponents off guard (in an earlier version of the official website, Justice was described as "The Gunman with Three Arms"), which explains how he decapitated Afro's father. His origins are unknown, but he claims that destiny designed him to attain all the headbands and thus gain enough power to rule the world as a god and bring an end to all the violence and killing via force. Justice's hidden third arm is what decapitated Afro's father, he tries to use this move on Afro during their fight but just before the final blow Afro has a flashback of his father's fight and sees the third arm decapitate his father. Justice was able to survive being nearly decapitated (an ironic reversal of the scene with Afro's father), and seemed able to control the Number One's throne room to some extent, but Afro manages to defeat him by slicing his body into many smaller pieces.

Justice returns several times in Season 2; first in Afro's dreams, seen nailed to a cross alongside Afro's father, then as a broken statue pointed out to Afro by Ninja Ninja and then once more in a non-speaking role, fully healed and meeting Takimoto, a mysterious masked man, during a solar eclipse. This small cameo has led many to believe Justice will be utilized again in a future plot.

During interviews in the DVD release, it is stated that Justice and Afro's father were in fact part of the same clan of swordsmen and indeed best friends; however, their differing views on the headbands and how to end the violence plaguing the world eventually drove them apart, leading to the final confrontation between the two that parallels the final fight between Afro and Jinno.

source: http://tv.ign.com/articles/720/720118p1.html