In Lifesigns: Surgical Unit, players take on the role of Tendo Dokuta, a second-year intern at Seimei Medical University Hospital in Japan. Throughout the game, Tendo learns how to take care of patients, friends, and possibly even himself. Dr. Kyosuke Swai, the director of the hospital, as well as Tendo's real father (which is revealed in the Japan-only release Kenshuui Tendo Dokuta) lands Tendo the job at Seimei, which is the most prestigious hospital in the country. Swai puts Tendo in charge of a new miracle drug called SPX, which has the capability of curing both cancer and AIDS. Helping Tendo in his tasks is a full cast of characters, most notably Dr. Suzu Aso, a respected heart surgeon as well as Swai's ex-girlfriend. Also in the game is Yuma Aoshima, a first-year intern at the hospital and a new love interest for Tendo.
Resembling something of a cross betwen the Phoenix Wright series and the Trauma Center series, Tendo interacts with patients and co-workers in such a way that requires presenting "clues" in order to further progress converstations. Most of the game is actually spent doing this, making it much more dramatic and story driven than the arcade-like action found in the Trauma Center series.
The other portion of the game actually involves surgery, which is very much like the surgeries found in the Trauma Center series. Players are challenged with finding problem spots on their patients using various methods, including talking to the patient as well as using a stethoscope. After the diagnosis, Tendo must operate on the patient in order to remove whatever it is that ails them.