Having premiered in the first Street Fighter in 1987, Ryu appears as the lead character in the game alongside his best friend Ken Masters. Further games from the series show Ryu to be highly focused on his training, aiming to become the strongest he can. However, his powers also attract several criminals who want to use him for their plans, such as M. Bison. In some games, Ryu has an alternative form known as Evil Ryu (殺意の波動に目覚めたリュウ Satsui no Hadō ni Mezameta Ryū, lit. "Ryu with the surge of murderous intent awakened", abbreviated Satsui Ryu in Street Fighter Alpha 3), who later goes by the name of the form's physical manifestation known as Kage (影, lit. Shadow), or in Japan has a full name Kage-Naru mono (影ナル者 lit. Shadowed One).
Ryu has been the lead character of the Street Fighter series since the first game and has appeared as a playable character in several crossover games involving the franchise, including the Marvel vs. Capcom series, Project X Zone, and the Super Smash Bros. series. He has also featured in manga and anime adaptations as well as the 1994 live-action film. Ryu has become one of gaming's most iconic fighting game characters, but his evil persona has been criticized for retaining most of his regular form's moves.