TOKYO MER is formed by order from the Governor of Tokyo. The name of the group stands for TOKYO Mobile Emergency Room. The members are emergency care professionals and they are to go to sites of dangerous accidents and disasters by ER car. Their ER car is a large vehicle equipped with the latest medical devices and an operating area. There, TOKYO MER saves lives of the injured.

Kōta Kitami is a doctor for TOKYO MER and its leader. He holds a strong conviction that, regardless of the dangers, he will go to accident sites to save lives.