Nami is the first member of the Straw Hat Pirates to appear in the anime series, but the third to appear in the manga. Likely one of the best navigators currently sailing the Grand Line, Nami acts in the roles of treasurer and quartermaster as well.
Along with Nico Robin, Tony Tony Chopper and Usopp, Nami is one of the smartest of the Straw Hats and the third smartest character during the East Blue saga according to Oda, the first being Ben Beckman of the Red-Haired pirates and the second being Captain Kuro. She is an excellent navigator and has the ability to recognize and analyze even the slightest changes in the weather through sheer intuition, thus saving the ship and the crew from the very unstable Grand Line weather on multiple occasions.
Her two favorite things are money and mikan (mandarin oranges), often translated to tangerines (the English manga uses "tangerines"), because of her love of her foster mother, Bellemere.
Nami's dream is to draw a perfect map of the world, a task not yet accomplished by anyone due to the harsh nature of the oceans in the Grand Line. The first map Nami plotted was the island Cocoyashi village at the age of 8.
Nami has a tattoo on her left shoulder which represents mikan and pinwheels (a homage to her past), where she used to have a tattoo for being a member of Arlong's Crew. Near the beginning of the series, Nami wore thick, low cut leather boots and a simple blouse. However, during the Arlong Park arc and thereafter, Nami wore open-toed shoes and more revealing outfits (With the tattoo no longer being a secret). She seemed to have abandoned the shoes for high-heeled boots as of Chapter 435. She usually pairs her tops with skirts with rings on them. Her overall physique matured suddenly (though this is, most likely, a simple change in style of artwork). Her fashion frequently changes as well as her hair style.
According to the author (in response to a fan's question), Nami's dress size was 37-22-34. The author has also replied to a fan's question to saying that right now Nami's measurements are as follows: Height 169 B 95 W 55 H 85, though her breasts seem to grow and then "reset" throughout the arcs (this is much more obvious in the manga). He has also said that Nami resembles a cat, that he uses the color orange to represent her, and she smells of mikan and money.
Personality
Along with Nico Robin, Nami is one of the smartest of the Straw Hats and the third smartest character during the East Blue Saga according to Oda, the first being Ben Beckman of the Red-Haired pirates and the 2nd being Captain Kuro. At the beginning of the series, Nami despised all pirates. She viewed them as nothing but bad people after losing someone close to her, only changing her mind after she met Luffy and Zoro.
Nami is greedy and will do anything for money, accepting any challenge that comes along. While she will send in Luffy, Zoro and the rest of the crew to meet the demand, the one thing she will not do is sell out a friend; no matter what the sum. She takes control of the amount of money the crew spends, ever aware of the crews spending habits (such as Luffy's desire to spend all they have on meat) and tries her hardest to avoid it getting spent all at once. To this end she is in complete horror whenever the rest of the crew wastes money. She is loyal to her money, but no matter how much she denies it, she is loyal to her friends first.
Nami's main concern when she is in trouble is herself first and usually has other members do her fighting, resulting in her fighting in fewer fights. She is a coward, though not on the same level as Ussop, her cowardice has more to do with staying alive rather then being afraid. She can be devilish at times and won't think twice about ditching the others to save her own life. However despite these outlooks on life she has a line she will not cross. Because of Nami's immoral limits, she has been known to stand her ground against anyone hurting her friends, abandoning her otherwise normal routine of trying to stay out of harms way.
Nami also has an obsession with fashion, as she is never seen wearing the same clothes. This was not present in the early chapters and started after the Captain Kuro arc. When Nami goes shopping, she sometimes goes to exquisite boutiques and tries on stuff, just to leave stating that she is searching for something more casual. She doesn't seem to have much modesty as she sometimes wears rather skimpy clothing, she even doesn't have any problems with men seeing her naked as she showed her body to the crew so they would stop watching her and Vivi and she changed her clothes in full view on a sea train, she also doesn't like people insulting her navigating skills.
Relationships
crew
Nami at first was excited to join the crew but grew more reluctant when she learned that Luffy is a pirate because of her disgust at pirates. She betrayed Luffy and even wished him dead before he formed a crew. Her original membership into the crew was just as an "alliance" with Luffy which she later ended to return to her home village, however by then she had become fond of the crew and found it was not so easy to just leave. However after Arlong's defeat she officially joined the crew, by then she had completely changed her mind on her fellow crewmates.
She soon came to respect Luffy's qualities as a leader, but often gets angry at his irrational thinking and short attention span. In such situations, she sometimes tends to get into violent outbreaks. Her sudden violent outbreaks may also be caused by traits of other crew members such as Roronoa Zoro's sleeping. Despite this, she trusts Luffy very much. Nami is also the only character Luffy entrusts with his hat.
She also often takes advantage of Sanji with his devotion to her, ordering him to do her bidding. Its also good to note that Sanji is the only male Nami refers to with an honorific(kun). She also uses Usopp to maintain her weapons (and wriggling out of paying him for his service). Zoro tries not to fall for her manipulative schemes, but ends up a victim like the rest, usually due to debt. The crew member she seems to get along best with is Robin, whom she also doesn't boss around, and even calls "nee-sama" or "nee-san" at times.
Friends
Back home, Genzo acted as a father figure to both Nami and Nojiko. He was shown very concerned about Nami's pose on her bounty attracting more perverts than bounty hunters, although he had an enlarged picture of it, himself. Amusing considering the fact that he is more concerned about her picture than Nami being arrested. The rest of the village still adores her.
Nami also shared a close relationship with Vivi, to the point of an almost sisterly bond. Like the rest of the crew, she was deeply upset about her leaving.
She also made a good friend of Lola the zombie warthog, to the point where she even help set Lola and Absalom up for marriage. Their friendship transcended over into the real Lola when Thriller Bark was taken down. Lola had a strange feeling she already knew Nami from somewhere else despite never meeting her before, Nami was just happy to see her friend. To date, Lola has been the only person Nami has willingly handed some of her treasure over to. Lola now regards Nami as a sister, to ensure her and her friends were safe she gave Nami half of her Biblicard for her mother.
Enemies
Nami is an enemy to the Marines as both a pirate and a member of the crew, as she carries a bounty on her head. Essentially, her biggest enemy was Arlong, but ever since his defeat she has become enemies of other villains, mainly because of the Straw Hats' battles along the Grand Line.
Family
Bellemere
She has comes to terms with the idea Bellemere was her mother. In life she never saw eye to eye with her adoptive mother at times, in death Nami deeply missed her due to the fact she knew Bellemere deeply loved her despite everything. Nami is seen drawing a picture of her after being forced into Arlong's crew.
She regularly visited her grave on the cliff top where she was buried and often thought about her. As she was leaving her home, Nami spoke as though directly to Bellemere and told an image of her that she was leaving, a short moment later as she walked out the door a force pushed her along and Nami is left wondering what just happened.
Nojiko
Although they didn't get along as children, Nami values Nojiko as the only person who loved and supported her through her years of stealing to buy the village. Though not related by blood, she supports Nami like a real sister.
Other
As an orphan, Nami may have other family. However considering the circumstances behind her origins with Bellemere and Nojiko and the fact Bellemere found both girls in a war zone, it seems unlikely this will ever be touched upon.
Abilities and Powers
Nami is a highly skilled navigator as well as being a talented cartographer. She has the innate ability to sense changes in the weather and can even predict the appearance of the supposedly unpredictable cyclones of the Grand Line even while running a high fever. This attribute proved useful during Nami's one-on-one "fight" with Eneru, where she managed to deflect several of the Goro Goro No Mi user's lightning based attacks using only the clima-tact. She is also an excellent thief and pickpocket who can steal small items such as keys on light encounters without the victim noticing (she is shown stealing even as a little girl).
Compared to her fellow Straw Hats, she is not as skilled in combat as she is lacking the strength and skill needed to defeat most foes. This led her to remain as a supporting member of the crew rather then a main fighter. Though she possesses moderate skill when wielding a Bo staff for self-defense long before she acquired the Clima-Tact and its upgrades. She shamelessly manipulated one of her crewmates to fight in her place, usually by blackmailing Zoro, charming Sanji, or ordering Luffy around
She relied mainly on a standard wooden staff throughout the East Blue saga and leading up to the Alabasta arc. Later, Usopp invents for her a weapon called the "Clima Tact" that allowed her to fight in a major battle for the first time in a nonsupporting role and landed her first major victory against Miss Doublefinger. Though this did not mean she stopped using her old tactics she employed before the Arabasta arc.
Currently, Nami has been given a Dial enhanced Clima-Tact, the "Perfect Clima-Tact", by Usopp. The new weapon was powerful enough to wipe out an entire group of soldiers and she also managed to defeat CP9's Kalifa, securing her place as one of the crew's most valuable members.
Other Techniques
Though infrequent, Nami has a couple of other moves that she can use to incapacitate (in more ways than one) her opponents.
Shiawase Punch, Happiness Punch): A "technique" that Nami uses to dispatch Peeping Toms while she bathes; she simply drops her towel, causing any male in the vicinity to collapse from a massive nosebleed. She also uses this as a get-rich-quick scheme, as she charges 100,000 Belly to anyone who sees her doing this.
Impact : Nami uses an Impact Dial to absorb attacks and then send them back at her opponents. This was the move she used to dispatch Hotori.