Armor King (II) is the younger brother of Armor King. Prior to the original Armor King's discovery of King, the two brothers were tag team partners in Mexico. For unknown reasons, the original Armor King never mentioned the existence of his brother to King or King (II). After the original Armor King was killed by Craig Marduk, the younger brother embarks on a quest for vengeance, which is only exacerbated when he discovers that King (II) has forgiven Marduk.
Armor King (II) joins the fifth tournament late (Tekken: Dark Resurrection) in search of Marduk. He defeats Marduk, but disappears before killing him. Following the tournament, both Marduk and King (II) are confused by Armor King's apparent return from the dead and decide to search for answers. This leads them to the sixth tournament (Tekken 6).
During the sixth King of Iron Fist Tournament, Armor King (II) reveals that he is the younger brother of Armor King and that he will never forgive Marduk. After the tournament, Armor King and Marduk continue their feud. A vicious battle ensues, which leaves both men hospitalized in critical condition and unable to compete at the beginning of the seventh tournament (Tekken 7).
Marduk recovers from his injuries first and attempts to kill Armor King in the hospital, but is stopped by King (II). Marduk decides to challenge Armor King to a Mask vs Career match in the tournament (Tekken 7: Fated Retribution). If Armor King wins, Marduk has to retire from fighting forever. If Marduk wins, Armor King must never use the title or mask of Armor King ever again.