Ryuji Takane, called Ryu, is the son of deceased professional boxer Gou Takane. He and his sister Kiku inherited their father's boxing talents; Ryuji gained physical strength and technique, Kiku analytical and strategic abilities. After their father's death, their mother Chiyo remarried an abusive alcoholic, Tomizou. When Tomizou violently assaulted Kiku and Chiyo, the siblings fled to Tokyo, promising to return once Ryuji achieved boxing stardom and rescued their mother.

In Tokyo, Ryuji initially resisted boxing despite Kiku's coaching. His perspective shifted after rival Jun Kenzaki humiliated him and took their father's boxing gloves. This defeat ignited Ryuji's determination to master boxing, aiming to surpass Kenzaki and honor his father's legacy. Under Kiku's rigorous training and guidance from a mysterious stranger emphasizing left-hand dominance, Ryuji developed foundational skills. His relentless spirit emerged during a brutal unofficial match against Kenzaki, where he endured severe punishment but repeatedly rose to continue fighting.

Ryuji's boxing style centers on the Boomerang Hook, requiring precise body rotation and timing. He later expanded his arsenal with Double Boomerang, Boomerang Square, Boomerang Telios, and Winning the Rainbow. His growth led him to compete in Japan's National Junior Boxing Championship, forming lasting rivalries with fighters like the comedic but powerful Ishimatsu Katori, the cunning pianist Takeshi Kawai, and the stoic former kendo practitioner Kazuki Shinatora. These battles culminated in Ryuji winning the national title, establishing him as Japan's top junior boxer.

After winning the national championship, Ryuji and his team faced international challenges. They accepted a match against Black Shaft, the U.S. Junior Champion, who assembled a non-boxing team including a death row inmate, a biker gang leader, and a beauty-obsessed hypnotist. Ryuji contended with prior injuries while upholding Japan's honor against these unconventional opponents. This confrontation preceded the Junior World Tournament, where Ryuji's team battled stylized national teams like Italy's mafia-led squad, France's effeminate quintuplets, Germany's science-obsessed fighters, and ultimately Greece's god-themed team. Ryuji's perseverance and signature techniques remained central to Japan's success.

Retiring from amateur boxing, Ryuji pursued a professional career. A year after becoming world champion, he accepted a final challenge from Jun Kenzaki to settle their rivalry. The match escalated into a brutal contest where both fighters pushed their physical limits. Ryuji emerged victorious but collapsed immediately after. Unable to stand, he insisted on attending Kiku and Kenzaki's wedding that same day. Assisted by Kenzaki, he arrived at the ceremony only to die in his sister's arms, his championship belt beside him and a smile on his face, fulfilling his childhood promise to bring pride to his family.

Ryuji's legacy endured through Kiku and Kenzaki's son, Rindo Kenzaki, the protagonist of the sequel series *Ring ni Kakero 2*. Orphaned after his parents' deaths, Rindo was raised by Ishimatsu Katori, who trained him using Ryuji's teachings and spirit as foundational inspiration.