Ryo first appears in Art of Fighting, where he sets off to fight Mr. Big to save his sister Yuri. However, as he does so, he is led to a mysterious man known as Mr. Karate. After beating him, it is revealed that Mr. Karate was his and Yuri's father, Takuma Sakazaki and that he was being coerced by Geese Howard into being his muscle in Southtown, having arranged Yuri's kidnapping to force his cooperation. Ryo, his family, and his best friend Robert Garcia then proceed to search for and fight Geese. After failing to kill Geese in Art of Fighting 2 (which leads up to the events of the original Fatal Fury), Ryo's role is reduced to a supporting role to Robert in Art of Fighting 3: The Path of the Warrior, as the latter leaves for the fictional Mexican town of Glasshill without warning, in order to help his childhood friend Freia Lawrence. Ryo's playable appearances after this are mostly in The King of Fighters series, often teaming up with Robert, Yuri, and/or Takuma, as part of the Art of Fighting Team. In The King of Fighters series, he mostly joins the tournaments to get funds for his family's dojo.
Though not originally from the Fatal Fury series, Ryo made secret playable appearances in two of its games, Fatal Fury Special and Fatal Fury: Wild Ambition, the latter of which sees him succeeding his father as Mr. Karate.
As a costume
Ryo appears as one of Round 4's DLC Mii costumes. He is a costume for Mii Brawler. When Ryo's Mii Costume is being demonstrated, he is shown jumping off Wario's bike on Omega Mario Circuit, referencing cutscenes from the original Art of Fighting (which, incidentally, are a popular meme in Japan). He is also shown performing Flashing Mach Punch and Onslaught, which resemble his Zanretsuken and Ryuuko Ranbu moves. The appearance of King K. Rool using his forward aerial attack in Mii Fighter Costumes #4 trailer is a reference to Jack Turner's Super Drop Kick from the Art of Fighting series.
As a background character
Ryo makes a cameo on the King of Fighters Stadium.
Ryo appears as an Ace class spirit. In his spirit battle, he is represented by a Mii Brawler. Prior to the version 8.0.0 update, this Mii Brawler approximated Ryo's design using the Fighter Uniform and the Isaac Wig; however, from version 8.0.0 onward, the Mii Brawler will use the Ryo DLC costume itself if it has been purchased.