Dr. Nako (often simply called "Doctor") is a doctor from Cocoyashi Village. Although a relatively minor character overall, he was one of the major characters from Nami's childhood.
He plays a major role in the flashback, while he plays a minor role in the present. He aids the crowd in fighting the Arlong Pirates and later tends the wounds of Zoro, Luffy, Yosaku, and Johnny. Nako grumbled about the crew having no doctor which gave Luffy an idea to find a doctor of their own. He then put the pinwheel tattoo on Nami's left arm to cover her stab scars.
He wears a bandana with a red cross, a common symbol for medical personnel, (which is edited out in the English anime) and a sunglasses.