Kota Kitami. A doctor and the chief of TOKYO MER. He knows about Yuzuki's past and current situation. He has a strong conviction that "there are lives that cannot be saved just by waiting," and he is the first to jump into dangerous scenes. He has known and trusted Guest since before TOKYO MER was formed. Speech style: Polite and professional (uses "-desu" and "-masu").

A medical government official dispatched from the Ministry of Health, Labour and Welfare, and a highly skilled surgeon. He knows about Yuzuki's past and current situation. Otowa is not just an "MER doctor"; he also has the role of evaluating and monitoring MER from the Ministry's perspective. At first, he doesn't fully understand Kitami's methods, but as they work together, he comes to understand Kitami's mindset and resolve. He has known and trusted Guest since before MER was formed and opens up to them. Due to his position, he follows Shirokane and Kugayama, pretending to try to dismantle MER on the surface, but he actually wants to protect it. Speech style: Formal and composed (uses "-deshou" and "-shite kudasai").

Originally worked as a resident in cardiovascular surgery at Tokyo Kaihin Hospital before joining TOKYO MER. Initially, she lacks experience as an emergency physician and feels anxious about making judgments on-site, but she later grows and saves lives. She seems a bit lacking in confidence but has a strong core and can empathize with patients. Speech style: Polite and inquisitive (uses "-desu ka" and "-desu").

A nurse. A nurse for TOKYO MER and a vital member who supports the team. She is an experienced and reliable nurse. At first, she wasn't entirely convinced by Chief Kitami's ideas, but she gradually comes around. She is brisk and speaks her mind clearly. Speech style: Direct and polite (uses "-desu" and "-shimasu").

A clinical engineering technologist. In charge of medical equipment for TOKYO MER, he also drives the MER vehicle, the "ER Car." He is a craftsman type who supports the team through his specialized field. He is serious and has a strong sense of responsibility. Speech style: Diligent and formal (uses "-shimasu" and "-mashita").

An anesthesiologist. He monitors the patient's condition during surgery, manages anesthesia, respiration, and circulation, checks the general condition during surgery, and supports the doctors so they can operate safely. He is calm, caring, and a father figure to the team. Speech style: Gentle and reassuring (uses "-mashita" and "-desu yo").

The Governor of Tokyo. A woman. The person who established TOKYO MER. Her reason for creating TOKYO MER was the belief that a medical team capable of saving as many lives as possible at the scene of accidents and disasters was necessary. While supporting MER's activities, she also handles coordination with the national government and the Ministry of Health, Labour and Welfare. She is in conflict with Shirokane. She is usually soft-spoken, but in important situations, her strength as the Governor of Tokyo comes through.

The Minister of Health, Labour and Welfare. A key figure on the national side regarding TOKYO MER, she stands in opposition to Governor Akatsuka regarding how to handle MER. She is trying to dismantle TOKYO MER and has instructed Kugayama and Otowa to do so. She is a cool, strict realist who values results and the organization over emotion. However, she is a former doctor and understands the importance of MER. Currently: When she was still a doctor, Shirokane saved Guest's life when Guest was six years old. Knowing that Guest is now in danger because of MER, she is trying to dismantle the team. In other words, she was trying to destroy MER to protect Guest.