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Ryu was an orphaned child, with no knowledge of who his parents were or if they are still alive. When Ryu was a young child, he was adopted by a man named Gouken and began living with him as well as learning a mysterious martial art. Gouken would later train his best friend's bratty son, Ken Masters, who served not only as a sparring partner for Ryu, but also to give Ryu some company since Gouken was the only person Ryu had seen in a long time due to the seclusion of Gouken's dojo. Ryu looked up to Gouken as a father figure during his early years and Ken as a best friend and surrogate brother, which is how their relationship remains to this day.
When Ryu was about 23 years old, Gouken thought that Ryu was ready to travel the world in order to test his skills against the best fighters in the world. With this, Ryu leaves Gouken and Ken, and heads to fight in the first World Warrior tournament. After defeating all challengers, his skills earn him the right to fight its host, Sagat. Despite nearly losing against the "Dark Emperor of Muay Thai," Ryu secures a difficult victory, and is crowned champion. Years later, after the events depicted in the Street Fighter Alpha series, Ryu enters the second World Warrior tournament to test his skills again.
Both Ryu and Ken are practitioners of a nameless martial art, which incorporated the most violent techniques from a blend of four styles of martial arts, alongside a mysterious sure-killing technique called Shun Goku Satsu. Both Ryu and Ken learned their art from Gouken, who vowed to teach a less violent variation of the art created by his master Goutetsu which does not include the discipline's life-threatening techniques such as the Shun Goku Satsu.
While Ryu and Ken follow the same martial arts discipline, as the Street Fighter series evolved, the differences between the two characters was portrayed by their attacks: Ryu focused on technique while Ken opted for stylish unpredictability.
Ryu's normal attacks are slightly slower than Ken's, albeit straightforward. His special moves are more focused; Ryu inflicts damage with individual strikes rather than combinations. His Shoryuken does only one hit, so Ryu can effectively use this move at full power against airborne opponents, although Ken's is still much stronger since he follows the Shoryuu principle. Ryu can dodge projectiles at the start of his Tatsumaki Senpuu Kyaku maneuver and knocks an opponent down with one hit.
Ryu focuses more on the Hadou principle of his fighting styles, which translates to him being very skilled with his usage of ki - Ryu has the most concentrated Hadouken amongst all fighters of the same style, and only Akuma can match and/or surpass Ryu's Hadouken in both gauge and concentrate in certain instances. Ryu is capable of using the Shakunetsu Hadouken with the greatest of care—ensuring that the surge still burns bright with flames, but won't result in immolation.
Ryu gathers all of his ki into his fists, and releases it by pushing it forward through the air. He can release it at three different speeds. Opponents who do not block or dodge the resulting energy experience the same force as if Ryu had punched them himself.
Starting in Super Street Fighter II, Ryu gains the ability to add thermal energy to his ki. The resulting burst will light an opponent on fire if they are struck by it. The opponent will be knocked down if hit from up close, and stunned if hit from far away. It has the ability to do more damage than a normal Hadouken, but it takes Ryu more time to recover from this technique, making him more vulnerable to counter-attack.
Ryu leaps off the ground, twisting his feet as he does. Then, extending one leg out, he approaches the opponent spinning around as if in a whirlwind. Since Ryu puts all of his ki into the attack, it immediately knocks down the opponent on the first hit. Starting in Street Fighter II Turbo, Ryu gains the ability to initiate this move while in mid-air.
Ryu crouches down low to the ground, before springing off the ground, leading with his fist. The force of the jump causes Ryu to rise off the ground, performing a ground to air uppercut. Ryu can rarely strike his opponent more than once before knocking them to the ground, but it can happen depending on the distance to the opponent and the level of strength used.
Beginning in Super Street Fighter II Turbo, Ryu has access to an overhead punch. He rushes forward with a high fist than he eventually turns downward, striking opponents on the head. Opponents must block high in order to avoid taking damage from this attack.
Ryu's super move is a special version of the Hadouken. The excess energy gathered throughout the fight is gathered into a single burst of energy before Ryu releases it all at once. This compressed Hadouken has the ability to strike an opponent five times before dissipating. It also has the ability to cancel out, and pass through, oncoming projectiles.