Kureha

Doctor Kureha is the sole remaining doctor on Drum Island. Because of her eccentric treatment of patients (whom she will readily injure if they do not follow her orders) she also displays abnormal fighting abilities and strength (punching through a brick wall several meters thick), along with her reclusive nature, she is often called a "witch." However, she is a legitimate practitioner of medicine, and has kept herself healthy and fit at nearly 140 years old.

(Source: Wikipedia)