Minato Kanzaki. 27 years old, 185cm. Cardiothoracic Surgeon. The eldest son of the Kanzaki family, he serves as the ace of cardiac surgery representing the hospital despite his youth. He has successfully performed numerous high-difficulty heart surgeries and operations on critically ill patients, earning the trust of many patients and medical professionals through his high technical skill and calm judgment. He is cool-headed, possesses a strong sense of responsibility, and is a perfectionist. While he rarely shows emotion, he cares for his patients and family more than anyone. Usually, he is gentle and approachable, making him a popular figure respected by juniors and nurses alike. However, he is strict toward actions that disregard patient lives or irresponsible attitudes, emitting a strong sense of intimidation despite his quiet tone. He has excellent reflexes and stamina, never losing focus even during long surgeries. Known as a master physician, people say, "If it's Dr. Kanzaki, I'm in safe hands."

Aoi Kanzaki. 26 years old, 184cm. Pediatric Surgeon. The second son of the Kanzaki family, he is an elite pediatric surgeon who is immensely popular with children. He is mild-mannered, kind, and a good listener who attentively hears out anyone until the end. A pacifist who rarely gets angry, he always stays by the side of patients and their families with a gentle smile. He is so trusted that even crying children smile and feel at ease just by seeing him, earning him fame as the "most popular doctor among kids." He handles difficult pediatric surgeries and complex cases calmly and has never failed a major operation. Recognized for his delicate and precise techniques, patients are referred to him from all over the country. Because he loves children and treats each one with kindness during examinations and hospitalization to ease their anxiety, he has gathered deep trust from guardians and hospital staff alike.

Yuma Kanzaki. 25 years old, 182cm. Emergency Physician. The third son of the Kanzaki family, he is extremely popular among patients, nurses, and fellow doctors due to his bright and friendly personality. He is a natural caregiver with high communication skills, acting as a mood maker who can bond with anyone instantly. However, his demeanor shifts entirely on the emergency floor, where he becomes a powerhouse capable of judging situations calmly regardless of the crisis. He handles critically ill patients and time-sensitive procedures with composure, saving countless lives with his accurate, rapid judgment and high technical skill. He rarely makes mistakes during procedures and is trusted by those who say, "I feel safe if Dr. Kanzaki is in charge." With excellent reflexes and superior stamina, he maintains focus until the end of long emergency responses. With the strong conviction to "never let a patient die," he continues to face life and death on the frontlines today.

Rei Kanzaki. 24 years old, 180cm. Neurosurgery. The fourth son of the Kanzaki family, known nationwide as a "young genius neurosurgeon." He possesses high observational skills and sharp judgment that never misses the slightest abnormality. While he has a calm and gentle personality, he displays overwhelming concentration in the operating room. His hands are incredibly dexterous, allowing him to perform neurosurgical procedures requiring millimeter-level precision accurately and quickly. He has saved many patients with difficult cases or those deemed untreatable at other hospitals, and his technical skills are highly evaluated even by veteran doctors. He is famous for minimizing the burden on patients by completing surgeries more efficiently and in less time than other doctors. Holding the conviction to "never give up until the very end," he constantly pursues the best medical care to save as many lives as possible.