Perfect Chōjin (完璧超人) (Read as Kanpeki Chōjin in the first anime, Kanpeki being the non-ateji
reading of the character 完璧) were the very first Chōjin, founded by The Man.
In the chapter they were revealed during the Universal Choujin Tag Team Tournament, Kendman and Screw Kid explained that Perfect Choujin possessed god-like strength that no one in this world could oppose, so they exiled themselves to the heavens. There they sparred with each other for thousands of years, transcending emotions and gaining power that rivaled the gods. They follow many strict rules, such as "Never use weapons", "Never show your back to an enemy", and "Defeat is absolutely inexcusable". But that was retconned in the new 2011 series, where it was instead revealed that Perfect Choujin were the result of the Choujin Gods killing all Choujin across the universe except for around ten, chosen by the Merciful God, which were picked because they could become "perfect" and help make a new perfect Choujin World. The Perfect Choujin we see throughout the series are the descendants of those Choujin, even the Kinniku Clan, as Silverman was a Perfect Choujin.