The second doctor of TOKYO MER and a medical technocrat from the Ministry of Health, Labour and Welfare. A cool-headed and ambitious man who stands in contrast to Kitami, he has his own ideals for medical policy. While he recognizes the necessity of TOKYO MER, he is scheduled to leave his post as second doctor to return to the Ministry as the MER Planning Promotion Department Director.

The Chief Doctor of TOKYO MER. An emergency physician who never gives up, he possesses immense courage forged from his experience in conflict zones and remote areas abroad. Driven by a childhood trauma, his policy is "waiting won't save lives," and he risks his own life to reach patients. His diagnoses are precise and his surgical speed is superhuman.

An intern at TOKYO MER, originally from the Cardiovascular Surgery department at Tokyo Kaihin Hospital. Her true goal is to become a cardiac surgeon. Initially bewildered by the chaos of emergency scenes and resistant to Kitami's risky methods, she grows proud of her role after witnessing his devotion. She is currently torn between pursuing cardiovascular surgery or stepping up as the second doctor to replace the departing Otowa.

A nurse at TOKYO MER. Highly experienced in emergency medicine, she serves as Kitami's right hand in time-critical situations. She has a positive personality and a strong spirit of challenge. A single mother with a daughter in preschool, she balances grueling emergency work and ward duties out of a passionate desire to save lives.

Kota Kitami's younger sister. She works for an NPO that supports hospitalized children and their families. As each other's only family, the siblings share a deep bond. She is the greatest supporter and understander of Kota's passion for emergency medicine.

A clinical engineer and paramedic for TOKYO MER. A self-proclaimed mechanical geek, he finds his greatest joy in maintaining medical equipment and vehicles. His creed is that the ultimate medical system is only complete when top-tier doctors, top-tier equipment, and top-tier engineers work as one.

The anesthesiologist for TOKYO MER. As the one who controls the patient's condition during surgery, he is the essential right hand of the lead surgeon. A family man with a gentle personality, he plays a fatherly role, warmly watching over the team members.

A nurse at TOKYO MER from Vietnam. She came to Japan under an Economic Partnership Agreement (EPA) to learn advanced nursing skills for her home country. A hard worker and diligent student, she has become fluent in Japanese within a few years and has mastered complex terminology. She loves Japanese anime and manga.