- Mortal Kombat 4: "Once a general in Shinnok's armies, Reiko lead the forces of darkness into the battle against the Elder Gods. Once thought killed during that onslaught, he resurfaces and joins the battle against Earth's forces."
- Armageddon Bio Kard: "Reiko has served Shao Kahn and Shinnok. He also served for a time as a member of the Brotherhood of Shadow. His skills in battle is legendary, though little else is known about this mysterious warrior."
Not much is known about him, save that his primary occupation is that of a general. In this capacity, he has served both Shinnok and Shao Kahn. He has also served as a member of the Brotherhood of Shadow. During Shinnok's war against the Elder Gods, he was presumed killed. He later resurfaced during the time of Mortal Kombat 4, but after Shinnok was defeated, he disappeared once again. He later emerged in Shao Kahn's army, to whom he has served until now. In his Armageddon bio card, John Vogel states that Reiko received the position of general as Shao Kahn approved of the fighter's ruthlessness, which he is said to look for in his soldiers.
Reiko apparently has great aspirations to one day replace the emperor, as it is described in Mortal Kombat: Deception's Konquest mode that he likes to sneak into Kahn's chamber room and wear his helmet. His own attire has a great similarity to Shao Kahn's. Reiko also states in the game that he will one day rule Outworld himself.
In Mortal Kombat: Armageddon's Konquest mode, Taven encounters Reiko in his war room in Shao Kahn's fortress. It is revealed here that, for unknown reasons, Reiko has an intense disliking of Quan Chi. Reiko tries to get Taven to join Kahn's army, having been impressed by his skills in combat, but Taven has none of this as he only intends to find and kill Quan Chi. Although Reiko is intrigued by the prospect, he had been ordered by Shao Kahn to protect the emperor's allies, which included the sorcerer, so he engages in battle with the intruder. Reiko is ultimately defeated, but as he limps away, he relishes in the irony that his failure would lead to the death of Quan Chi. He later appears in the Battle of Armageddon, where he joins the Forces of Darkness, but is ultimately killed in the process.
- Mortal Kombat 4: Reiko is seen when a portal opens up. He steps through the portal, which leads him to Shao Kahn's throne room. Shao Kahn's helmet is eventually lowered onto Reiko's head.
- Armageddon: "When the godlike power of Blaze flashed through Reiko's body, he felt his old desire for power returned more intensely than before. Now more powerful than even Shao Kahn, Reiko defeated the emperor and claimed his helmet. As he placed it on his head, his body fused with it, transforming him into a warlord of unprecedented savagery!"