From the Manufacturer

Nami is a fictional character in the One Piece franchise created by Eiichiro Oda. She is based on Ann and Silk, two characters from Oda's previous manga Romance Dawn. She is introduced as a thief and pickpocket who possesses skills to tell the climate and draw sea charts. At first, she is a subordinate of the fish man Arlong, but she is eventually freed of this service and permanently joins Monkey D. Luffy for her dream to write the complete map of the Grand Line. She is the first main character to appear in the anime series.