Hua Tuo, styled Yuanhua (Pronounced Who-Ah Tw-oh, You-Ah-n who-ah) was a medical professional in the Late Han/Three Kingdoms eras. Not much is known about him, as much information was lost to history. What is known was that he was able to perform what seemed like miracles on the sick and wounded at the time. 

He was a masterful physician and an acupuncturist. He was also a surgeon, and perhaps the first man in China to use anaesthetics for patients. 

He will be around 44 or so at the beginning of the story, working as a traveling doctor.