Doppo Orochi is a major supporting figure in the martial arts world of Baki. He is a tenth dan karate grandmaster and the head of the Shinshinkai Karate School, an organization widely recognized as one of the most powerful karate institutions in the world. Having practiced martial arts for roughly fifty years, he is regarded as one of the strongest characters in the series and one of the few people capable of standing toe to toe with Yujiro Hanma. Over his long career he has earned several nicknames, including God of Martial Arts, Man-Eating Orochi, and Tiger Killer, titles that reflect both his legendary status and the ruthlessness he can show in combat. He is also the founder of Orochi-ryu Karate and is considered a living symbol of modern karate.

Doppo's background is rooted in the world of underground combat. He is a veteran of the secret fighting wars and serves as the director of the Shinshinkai organization. His martial arts philosophy is practical and battle-oriented rather than ceremonial. He trains his students harshly, regularly fighting them to keep them sharp, and he personally practices every karate technique at least one thousand times a day. This relentless devotion to fundamentals is a defining trait of his character. In spite of his brutal fighting style, he is portrayed as a devoted husband to his wife Natsue and a caring father to his adoptive son Katsumi Orochi, a young karate prodigy who follows in his footsteps.

In terms of personality, Doppo is disciplined, proud, and completely committed to the pursuit of strength. He approaches fighting with a calculating mind, carefully studying his opponent's stance, style, and techniques before engaging, and he is often able to decipher the secrets of unusual abilities relatively quickly. Once a fight begins, he is cunning and willing to do whatever it takes to win, showing a cruel streak that includes pulling out an opponent's claws or cutting off ears without hesitation. Despite this ferocity, he is also a mentor figure who earns genuine respect from those around him, including Baki Hanma, the series protagonist. Doppo takes a personal interest in Baki's rise and serves as one of his mentors, watching over his development as a fighter.

His role in the story is that of an experienced master and key ally who consistently represents the pinnacle of traditional karate against a wide range of extraordinary opponents. He participates in the underground arena tournament, where he defeats fighters such as Richard Filth and Yu Amanai before losing a brutal match to fellow master Goki Shibukawa. That loss becomes an important turning point for him, as he decides to close down his dojo and begin his training all over again from the basics, demonstrating his humility and his refusal to accept stagnation. Earlier in the series, he engages in a proper fight with Yujiro Hanma, who gouges out his right eye and kills him by stopping his heart. Doppo is later revived by the surgeon Kureha Shinogi, and he carries permanent scars from the encounter, including the loss of his eye.

Later in the story, Doppo faces the escaped convict Dorian, who manages to cut off Doppo's hand using a concealed wire blade projected from a lighter. Doppo eventually avenges this loss alongside Katsumi and the Chinese martial artist Retsu Kaioh when they track Dorian down. Shortly afterward, however, Dorian escapes from the hospital and uses an explosive implanted in his hand to blow off part of Doppo's face, an attack that he survives but that leaves him heavily scarred. He later returns to battle against Mohammad Alai Jr., continuing to prove that even with his accumulated injuries he remains an elite fighter. Doppo also serves as the protagonist of the spin-off manga Baki Gaiden: Kenjin, which explores his past and his personal journey as a martial artist.

Doppo's fighting ability is rooted entirely in karate, but his mastery elevates the style to superhuman levels. He possesses a formidable arsenal of techniques, including the Five-Step Striking Method, a rapid five-hit combination that deals heavy damage; Scattered Eyes, a method of flexibly moving the eyes to track and dodge attacks from all directions; and Sanchin, an ancient defensive stance achieved through breath control that is said to withstand nearly any attack when fully mastered. He also uses the Tiger Mouth Fist, a strike delivered with the webbing of the hand to the area between an opponent's nose and eyebrows that temporarily robs them of vision and clear thought. His other signature techniques include the Wind Grinding Kill, which dislocates the opponent's jaw, the Six-Wave Return, which strikes the skull with enough force to split its sutures, and the Bodhisattva Fist, a punch of immense power that carries no killing intent. His defensive abilities include the Karate Air Wall, a technique said to represent the pinnacle of receiving techniques and capable of defending against arrows, guns, and even flamethrowers, and the Non-Existent Technique, a devastating attack that should not exist within karate and can only be used when his life is genuinely threatened.

Doppo also demonstrates extraordinary physical conditioning outside of named techniques. His hand blade strikes are so refined that in demonstrations he can cleanly cut wine bottles, wooden planks, and even wire without leaving burrs. His feet and toes are trained to be as sharp as blades and can pierce through an opponent's muscles, turning any area struck into a fatal injury. In one demonstration at a Shinshinkai tournament, he was sealed inside a large concrete sewer pipe and proceeded to demolish it with his bare hands and feet. Taken together, his background, personality, relationships, and abilities paint a portrait of a martial artist who has dedicated his entire life to karate, who has survived some of the most brutal battles in the series, and who continues to embody the ideal of the warrior through constant training and adaptation.