Metal Black is one of the villains from Red's storyline in SaGa Frontier.
One of the Four Emeperors of Black X, Metal Black is actually a robot built by Dr. Klein. His base is located in Kyo, where is hidden a drugs factory. Though he is a robot, Metal Black learned to value life and respect his adversaries.
When Red blows up the drugs factory, Metal Black challenges him as he escapes the place, but ends destroyed. Dr. Klein rebuilds him and leaves him on watch in the Black Ray, Black X's personal ship. Red infiltrates the Black Ray in order to reach Black X's base, but stumbles upon Metal Black, who pursues his inside the ship. The two fight again, but Metal Black activates the self-destruction sequence of the ship. Red and his friends manage to escape the explosion and reach the base. Red, transformed into Alkaiser, confronts Dr. Klein, who shows Alkaiser his final upgrade on Metal Black, who now has all data on Alkaiser uploaded into his memory. Dr. Klein orders Metal Black to attack Alkaiser, but Metal Black asks Dr. Klein to allow Alkaiser to recover, to which Klein reluctantly agrees. Alkaiser defeats Metal Black for the last time, recognizing his prowess and wishing he had used his powers for good.