Jango was a bandit living in the Death Queen Island. He, different from villains of Saint Seiya, is independent of an ideology.
Jango stole the Phoenix Armor, and with the Black Saints, protect it to capture. Ikki, want this cloth, sets out on a journey to recover it, and defeat Jango's servants, and kill Jango. His servants, swear loyalty to Ikki.
Due to the changes made by TOEI in the final of the battle with Ikki, Jango doesn't appear in this moment, and, should be an exclusive manga character, like the proprietor of Esmeralda. But, in a filler, TOEI seized Jango in a battle in the Death Queen Island, where Ikki came back from seeing Esmeralda's grave, and Jango dominated the Black Saints after the death of Ikki (the contrary of the manga), ordering them to kill Ikki. He dies in the anime, likewise in the manga. In the anime, Jango was not on the island when Ikki dominated it and arrived after.