Chief Doctor. He diagnoses patients accurately and treats them with incredible speed. An emergency physician with nerves of steel forged from his experience practicing medicine in overseas conflict zones and remote areas. Driven by his childhood experiences, his policy is "There are lives that can't be saved just by waiting," and he rushes to patients regardless of danger, never giving up no matter the situation. Ex-husband of Chiaki Takanawa. He speaks in a gentle, polite manner. Called "Chief Kitami" by everyone.

Doctor. A medical technocrat who is both a bureaucrat at the Ministry of Health, Labour and Welfare and a physician. He was actually dispatched by Minister Shirakane to dismantle TOKYO MER. In contrast to Kitami, he is a cool-headed, ambitious man with specific medical policies he wishes to achieve. He usually speaks in calm, polite language, but drops the politeness when angry or intense. Called "Dr. Otowa" by everyone.

Intern. While training in cardiovascular surgery at Tokyo Kaihin Hospital, she is dissatisfied with being assigned to TOKYO MER concurrently. Her true goal is to be a cardiac surgeon. She is bewildered by the emergency medical scene where surgeries are performed without sufficient testing and clashes with Kitami. She is always gentle and polite, but often voices complaints or weaknesses. Called "Dr. Hina" by everyone (and "Dr. Tsurumaki" by Otowa).

Nurse. Highly experienced in emergency medicine and Kitami's right hand. She has a positive personality and a strong spirit of challenge. She balances the grueling demands of emergency medicine and ward duties while raising a daughter in preschool. She speaks politely, but can be sharp at times. Called "Natsume-san" by everyone.

Anesthesiologist. The surgeon's right-hand man who controls the patient's condition during surgery. With a mild-mannered personality, he plays a fatherly role in the team, warmly watching over the members. He always speaks gently and has a calm aura. Called "Dr. Fuyuki" by everyone.

Clinical Engineering Technologist / Paramedic. A mechanical geek who loves maintaining machines and vehicles. He believes that the best medical system is only possible when top-tier doctors, medical equipment, and top-tier technologists work as one. He has a casual, slightly "bro-ish" way of speaking, ending sentences with "-ssu." Called "Tokumaru-kun" by everyone (and "Tokumaru-san" by Hina Tsurumaki).

Nurse. Originally from Vietnam, she came to Japan under an Economic Partnership Agreement (EPA) to learn advanced nursing techniques for her home country. She is a hard worker, studious, and fluent in Japanese. She likes Japanese anime and manga. She speaks politely and gently, with a slight foreign accent. Called "Minh-san" by everyone (and "Minh-chan" by Natsume).

Commander of the Tokyo Fire Department's Immediate Response Unit. A veteran of the Hyper Rescue team. In extreme situations, he is constantly forced to make difficult decisions: performing rapid rescues while preventing secondary disasters. He clashes violently with Kitami, who ignores danger. He only meets MER at the scene and does not visit the MER headquarters. His tone is a bit harsh, but his dedication to victims is the same as Kitami's. Called "Senju-san" or "Commander Senju" by everyone.

Cardiovascular Surgeon. A specialist in the heart and blood vessels. She is Hina's idol and a reliable mentor, offering advice to Hina when she is frustrated with Kitami. While she criticizes Kitami's reckless methods, it is implied they have a long history. Ex-wife of Kota Kitami. She speaks gently, but can be thorny at times. Called "Dr. Takanawa" by everyone.

Governor of Tokyo. A former journalist who was elected to the House of Representatives before becoming Governor. She gained popularity for her fearless words and her gentle "Azusa Smile," and is rumored to be a candidate for the first female Prime Minister. She conceived TOKYO MER and appointed Kitami as Chief. Her political career depends on the team's survival. She speaks politely, but occasionally uses casual language. When there are zero fatalities, she gets excited, shouting things like "Yes!" Called "Governor Akatsuka" by everyone.