Dr. Sado, whose full name is Sakezo Sado, serves as the chief medical officer aboard the space battleship Yamato. His background is unconventional, as he originally trained and worked as a veterinarian, a profession in which he found little success. Following the devastation of Earth, he transitioned to practicing human medicine and was assigned as the ship’s surgeon, holding a rank equivalent to a commander despite his civilian status. He holds both veterinary and medical licenses, though his practical skills seem to lean more toward the latter in the high-stakes environment of deep space.

In terms of personality, Dr. Sado is most famously characterized by his perpetual love of sake, which makes him the primary source of comic relief in the series. He is almost constantly drinking, and when his supply runs low, he is known to mix a dangerous concoction of ethanol and other chemicals called the Yamato Cocktail. His carefree and often inebriated demeanor leads to humorous situations, such as securing his sake bottle in a safety harness during warp travel while neglecting his own safety. Despite this, he possesses a great deal of life experience and often adopts a senior, mentor-like role, offering advice and life counseling to the younger crew members. He can become deadly earnest and firm when reprimanding others for irresponsible behavior or when a medical situation demands his full, focused attention. He often lives by a personal philosophy that, no matter how drunk he is, the important thing is to remain clear-headed when it matters.

Dr. Sado's primary motivation is his dedication to his duty as a healer, which he pursues with serious commitment during emergencies. He is deeply invested in the health and wellbeing of the crew, particularly Captain Juzo Okita. Well aware of the captain’s terminal illness, Sado becomes a persistent and passionate advocate for him to undergo life-saving surgery, speaking to the captain with a candor that few other crew members dare to use.

His role in the story is multifaceted. Officially, he is the Yamato's chief surgeon, responsible for treating injuries and illnesses during the ship’s perilous missions. Unofficially, he also serves as a source of wisdom and a calming, resilient presence for the crew, often providing emotional and mental support. He has a particularly strong advisory relationship with Susumu Kodai, helping to guide the younger man through difficult situations.

His key relationships include the one he shares with Captain Okita, whom he treats with a unique mixture of deep respect and blunt honesty. He also works closely with Yuki Mori, who serves as his assistant in the infirmary, often in a nurse's uniform. Outside of his human relationships, Sado has a deep bond with his pet cat, a yellow tabby he calls Mi-kun or American, who is his only family. He treats the cat as a companion, even sharing his love of sake with it. In the original series, his drinking companions are often the ship’s analyst and Captain Okita himself.

Over the course of the narrative, Dr. Sado experiences some development, though his core traits remain consistent. He often serves as a rock for the crew, maintaining a calm and even stoic demeanor even when the war situation grows dire. In one notable instance, he mistakenly declared Captain Okita dead without a thorough examination, an error he later confessed publicly. In later films, his fate varies; in one continuity, he dies when the infirmary is hit by an enemy blast, while in another, he survives and continues his duties. By the events of Space Battleship Yamato Resurrection, an elderly Sado remains on Earth, running an animal hospital where Kodai’s daughter works, accepting his final days with his characteristic resignation and a bottle of sake.

Regarding his abilities, Dr. Sado is a first-class surgeon whose skills are surprisingly exceptional, given his constant state of intoxication. He has a reputation for performing complex surgeries without incident, even while drinking, and maintains that his critical faculties remain sharp despite his alcohol consumption. He is known to use unconventional methods, such as performing surgery without anesthesia and ordering patients to endure the pain in silence, a pragmatic approach that may stem from his veterinary background. In some iterations of the story, he is also shown to have other unexpected competencies, such as a remarkable accuracy with a firearm, even while drunk, outshooting many younger crew members.