He was the former leader of the Resistance movement in Outer Heaven. He later operated as the mercenary Black Ninja in Zanzibar Land.
In "Metal Gear 2: Solid Snake", he is better known by the war alias Black Ninja.
Kyle shares a striking resemblance to Gray Fox, another anti-villain in the Metal Gear series. Both were originally war operatives and allies to Solid Snake, were forced to become physically peaked ninjas and fought Snake before dying yet redeeming themselves.