He is a modern day ninja and a master of the Bushin style and is best friends with Cody Travers. In the original game, he assists Cody and Mike in their quest to destroy the Mad Gear Gang and save Jessica, Mike's daughter and Cody's girlfriend.
Although he doesn't appear in the sequel, it is stated that he is the fiancee of Rena, the elder daughter of his Bushin master Genryusai. Rena is only mentioned in this game and it is unknown if they are still together.
Guy participates in the Street Fighter Tournaments as he often senses a presence of evil because of M. Bison. This makes him an ally to the psychic, Rose.