Raiden is the codename of the rookie operative recruited by FoxHound to liberate Big Shell from the terrorist organization Dead Cell. While never experiencing actual combat, he is a veteran of over 300 VR missions, including simulations of the Outer Heaven, Zanzibar, and Shadow Moses campaigns. His superiors at Foxhound, including Colonel Roy Campbell, feel he has the potential to become the next Solid Snake. Which is ironic since Raiden shares similarities to Grey Fox.
Raiden is outfitted in a state-of-the-art stealth outfit known as a "Skull Suit," which is equipped with electro fiber technology and a large array of sensors known as "Smart Skin" that can detect injuries and communicate with the nanomachines in his body to create a feedback system. Raiden's intravenous nanomachines also serve to provide communications with Foxhound and access links to security nodes inside Big Shell.
Raiden has no known family and his only close acquaintance is his girlfriend Rose, who acts as his mission analyst for the Big Shell operation. Eventually he found out that Rose gave birth to his son named John who's nickname is 'Little Jack'.
Before being recruited by FoxHound, Raiden was in the U.S. military as part of the Army's Force XXI trials. His past before joining the service is unknown, even to him, as he suffers from an unrecognized form of Dissociative Amnesia.
During Liquid's Insurrection, Raiden was outfitted with a highly advanced cyborg suit which gave him a higher degree of strength, speed and agility. He eventually fought Vamp in Shadow Moses while Snake was keeping the Gekko at bay. However, before these events happened Raiden saved Olga's daughter Sunny from the Patriots gave her to Otacon and Solid Snake to look after her.
During the events of Big Shell, Solidus Snake recounts the events of Raiden's past. Raiden was orphaned during the Liberian Civil War in the late eighties, and Solidus was quick to adopt the child. By 1990, at only the age of ten, Raiden was a merciless child soldier, adept in the art of war and genocide.
Raiden remembers none of this because he undergoes extensive treatment, such as drugs, brainwashing, and synaptic nano-manipulation to suppress these memories when he is taken in by The Patriots.