Ryo Sakazaki, son of Takuma and Ronnet Sakazaki, trained rigorously in martial arts from childhood under Takuma’s guidance. This instilled a core principle: strength defines personal worth through self-reliance. Robert Garcia joined their dojo, becoming both sparring partner and close friend. Tragedy struck on Ryo’s tenth birthday when his mother died in a car accident. Takuma vanished mysteriously soon after, forcing Ryo to shoulder responsibility for his younger sister, Yuri. He supported them through construction work and street fighting. Initial struggles gave way to renown; perseverance and his commitment to protect Yuri earned him the title "The Invincible Dragon."

When crime lord Mr. Big, acting for Geese Howard, kidnapped Yuri, Ryo and Robert launched a search across Southtown. They found critical information from King, a bouncer. After defeating Mr. Big, they confronted the masked fighter Mr. Karate. Ryo overpowered him, but Yuri intervened as he prepared a final blow, revealing Mr. Karate as their father. Takuma explained Geese Howard had coerced him into criminal work to ensure his children's safety. The confrontation reunited the family after eleven years.

Ryo later retreated to the mountains for intensive training. Accepting an invitation to Geese Howard's martial arts tournament as a test of his abilities, he advanced to the finals. There, he rejected Geese's offer to join his criminal organization and defeated him in combat, though Geese escaped unharmed. This victory did little to dismantle Southtown's underlying threats.

Subsequent years saw Ryo shift focus toward mentoring and expanding the Kyokugenryu legacy. He inherited the mantle of Mr. Karate from Takuma, symbolizing his mastery. He oversaw dojos in Southtown and Mexico, training students like Marco Rodriguez and Khushnood Butt. Participation in recurring tournaments became essential for funding, as the dojos struggled financially despite periodic enrollment surges following high-profile victories. Enrollments often dwindled due to harsh training regimens or unexplained vandalism.

Ryo frequently teamed with Robert Garcia, Yuri, or Takuma in tournaments, though he consistently opposed Yuri's involvement, citing safety concerns. His stance softened over time as Yuri proved her capabilities. He also invited King to join their team, creating tension with Robert, who preferred Yuri's participation. Observing mutual respect between Ryo and King, Takuma mistakenly interpreted it as romantic interest and encouraged their partnership.

Decades later, the family opened a barbecue restaurant with Richard Meyer's support. Frustrated by their complacency and neglect of martial arts discipline, Ryo donned the Mr. Karate mask as Mr. Karate II. He demanded the family recommit to training in the mountains, leaving the restaurant under Marco Rodriguez's management.

Personality-wise, Ryo embodies seriousness and loyalty toward martial arts and family. His disciplined upbringing contrasts with Robert Garcia's flamboyance and Yuri's trend-focused demeanor. He openly acknowledges limitations in intellect and natural talent but views them as obstacles to overcome through relentless effort. Protective instincts toward Yuri clash with his recognition of her independence, causing internal conflict. His dynamic with King involves mutual professional respect; her unspoken romantic interest surfaces when he invites her to teach at the dojo, which he misinterprets as enthusiasm for Kyokugenryu.

Ryo's fighting style is Kyokugenryu Karate, emphasizing powerful punches, judo throws, and precise ki manipulation. Signature techniques include the projectile-based Ko'ou Ken, the multi-hit Zanretsuken, the concentrated energy blast Haoh Shou Kou Ken, and the rapid-strike finisher Ryuuko Ranbu. Later, he incorporated defensive techniques like the Joudan Uke parry to counter faster opponents. Beyond combat, he restores motorcycles, practices carpentry, and cultivates vegetables, reflecting a self-reliant lifestyle.