Dr. Sakezō Sado serves as the chief medical officer aboard the space battleship Yamato, a position he assumed after an unsuccessful career as a veterinarian. Despite his civilian background and initial lack of success treating animals, his medical skills are considered first-class, and he holds a rank equivalent to a commander in recognition of his expertise.

In personality, Dr. Sado is most frequently a source of comic relief, largely due to his profound and ever-present fondness for Japanese rice wine, sake. He treats his sake bottle like a dear companion, often securing it in his seat during dangerous warp maneuvers while he himself clings to a table for safety. This carefree and often inebriated exterior, however, masks a deep seriousness and dedication to his medical responsibilities. When a patient's health is at stake, he becomes intensely focused and can adopt a stern, admonishing tone, particularly when chiding what he perceives as irresponsible behavior.

Dr. Sado's primary motivation is the care of the Yamato's crew. This is most powerfully demonstrated in his persistent efforts to convince the ailing Captain Juzo Okita to undergo life-saving surgery, advocating for his captain's health with a frankness that few other crew members dare to show. He also willingly provides advice and life counseling to younger crew members, such as Susumu Kodai, acting as a resilient senior figure.

In the events of Farewell to Space Battleship Yamato, Dr. Sado's role is significant both in quiet moments and in the film's climax. He participates in a memorial gathering for the late Captain Okita at Hero's Hill, arriving early to sit at the base of the captain's statue and drink sake with his pet yellow tabby cat, Mimi. During the formal salute, his gesture is notably traditional, contrasting with the rest of the crew. After the ceremony, he expresses concern to the others about potential new threats to Earth, wondering if Okita's spirit might be sending them a warning. Later, when the crew decides to mutiny against Earth Defense Command to take the Yamato into battle against the White Comet Empire, Dr. Sado joins them and even vouches for Hajime Saito and his Space Cavalry unit, advocating for their inclusion on the mission. As the Yamato engages in its final, desperate assault, Dr. Sado remains at his post in the infirmary, where he is ultimately killed by an enemy explosion.

Dr. Sado shares several key relationships. His dynamic with Captain Okita is one of open candor, allowing him to speak as a peer and a concerned physician. He shares a close bond with his cat, Mimi, who accompanies him everywhere, even mimicking his salute and sharing his taste for sake. He also has a professional relationship with Yuki Mori, who often serves as his nurse and assistant in the infirmary.

Across the narrative, Dr. Sado shows little development in his personal habits but is consistent in his reliability. One notable moment of growth is his public confession of a past medical error: after Captain Okita collapsed, Sado declared him dead without checking his vital signs, a misdiagnosis from which he later had to recover. This incident highlights his fallibility and his integrity in acknowledging it. His medical approach can be unconventional and pragmatic, sometimes harkening back to his veterinary roots, such as performing surgery without anesthesia and ordering patients to endure the pain.

Regarding notable abilities, despite his constant drinking, Dr. Sado's surgical skills remain unimpaired; he claims to keep his mind clear when it matters most. He is capable of performing emergency procedures even while the ship is taking heavy damage during combat. Beyond medicine, he has demonstrated unexpected competence in critical non-medical situations, including the disarming of mutineers.