Ryu, a Street Fighter from Japan, is usually a silent, humble, and serious individual; which is often juxtaposed against the light-hearted, fiery persona of his best friend and oldest rival, Ken. He wanders the globe with the goal of completing mastery of his martial arts, and takes both travels and training very seriously. For Ryu, the training and mastery that come from the fight are all that he requires for satisfaction, declining the more material trappings of his various accomplishments as a fighter and simply moving to his next challenge once he is victorious. Though he does not seek the role of a hero, he possesses a similarly strong sense of justice as well. Due both to this “wandering warrior” persona and being raised far away from modern-day culture, Ryu often appears boring or detached to others. Deep down, he is a kind and good-hearted person who, on rare occasions, shows a sense of humor (albeit a bad one). He also respects others with skills equal to his own.

Sound like he does in Smash Bros. or Street Fighter 4, check this link for his sound reference: http://www.behindthevoiceactors.com/voice-compare/Street-Fighter/Ryu/

Give him a medium to medium-low pitch voice.