She respects Luffy's qualities as a leader, but often gets angry of his irrational thinking and short attention span, but she trusts him deeply. Even though Nami has deceived the crew, Luffy still trusts her enough to allow her to safe-keep his precious straw hat. Nami is almost always the one who gives orders on the ship (much to the Zoro's resentment) because Luffy's innocent nature prevents him from being able to give orders. She often comically beats or hits her other crewmates for their nonsense, which occurs quite often. This may also be caused by traits of other crew members such as Zoro's sleeping, Usopp and Chopper acting childish etc. Acting as the "mother" of the crew, Nami doesn't understand or approve of the boys' often macho attitudes and principles. These are the only situations where Nami doesn't get the final word, as seen when she tried to talk sense into Luffy and Usopp's great fallout. Nami is good friends with Nico Robin, the only other female and sensible person currently on the Straw Hat crew. Robin is the only person Nami doesn't try to boss, and Nami has stated that Robin is the only person who understands her.

Nami is greedy and will do anything, aside from endangering her friends, for money, due to her past - After having gathered money all her life, Nami is naturally accustomed to it, stating that after being freed from Arlong, the money is all hers nows, but thinks of her friends as more important. She is very manipulative, and often takes advantage of Sanji for his devotion to her and Usopp to maintain her weapons. Roronoa Zoro tries not to fall for her schemes, but ends up a victim like the rest, usually due to debt, or taunts from Nami about a why a "great man" like him couldn't keep his word or do one simple task. Nami also tries to avoid fights this way and will try to hide in groups or send others before her. However, since the invention of her Clima Tact (A weapon that forms weather patterns, also called the Weather Enforcer in the English dub), she is now seen fighting her own battles instead of becoming the 'easy target', as she doesn't want to be the one being saved anymore.

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. It seems she is more fond of her orange trees than the money; when the crew returned to Water 7 and had their belongings returned to them, Nami was overjoyed at seeing the trees that she hugged one of the tree with tears coming out of her eyes, but did not hug the money like she usually does. And when Franky was talking about what he did with the 200 million belies that he stole, it was Sanji who was upset, rather than her. This shows that Nami cares more about those close to her than money and also hints to the possibility that she is becoming less greedy.

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 Grand Line. The first map Nami plotted was the island Cocoyashi village is on.

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. This is similar to Bulma, the main female character of Dragon Ball (Eiichiro Oda's favorite manga), who is never seen with the same hairstyle. 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. Nami also appears to have an inhumanly high tolerance for alcohol, even more so than Roronoa Zoro. In Whiskey Peak, she was seen out-drinking 14 different Baroque Works members without showing any signs of drunkenness at all, losing only because she pretended to collapse in order to fool the bounty hunters, possibly because of her determination to win the prize money.

She has her own sad story.

Nami is an orphan found by Belle-Mère, a female Marine, on a battlefield as an infant. The marine adopted her along with Nojiko, another child, and the three became as close as a real family. However, this ended when the infamous Fish-Man pirate Arlong took over Cocoyashi Village (or Coco Village in the English language manga and dub), their adopted hometown, and imposed a fee on every single adult and child in the village in order to 'live'.

Since Belle-Mère could not pay for her entire family's monthly fee for living, Belle-Mère was used as an 'example' by Arlong to demonstrate to the townspeople what will happen to them if they ever go against him or fail to pay the fee. Belle-Mère is then brutally murdered by a shot from Arlong in front of Nami and Nojiko. Nami was then kidnapped and forced to become a cartographer for Arlong. However, Arlong struck a deal with Nami: if she brought him one hundred million Belli (the form of currency in One Piece), he would free her village.

Nami realised then that if she ever told the citizens of Cocoyashi Village, then she would might be bringing them false hope, as she couldn't possibly guarantee her success, and knew that one day she would might be forced to run away. Although Nojiki eventually told them, Nami lived in the belief that they still hated her for joining Arlong's crew. She then swore upon to never again ever ask anyone for help.

She spent eight years making maps and stealing treasure from pirates in order to buy back her village.

She doesn't have powers but she is a highly skilled navigator and 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. She is also an excellent thief and pickpocket who can steal small items such as keys on light encounters without the victim noticing.

Nami is not as skilled a combatant as some of the Straw Hats, although she is able in wielding a staff, and can take down normal pirates or marines with few problems. She usually ends up fighting a female villainess. She is able to unleash quick and moderately powerful strikes, and during the Alabasta arc and beyond, uses a weather manipulating staff Usopp created for her, the Clima Tact, to fight. The weapon is actually partly used for party tricks, but using certain combinations, Nami turns the tomfoolery of Usopp into a deadly force to be reckoned with, and is able to defeat one of the strongest members of the Baroque Works, Miss Doublefinger (Mr. 1's partner agent, and Baroque Works' second strongest female agent); one of the CP9 members and two lieutenants of Enel's Enforcers, Hotori and Kotori, with the help of Gan Fall.

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; with the Perfect Clima-tact, she also managed to defeat CP9's Kalifa, securing her place as one of the crew's most valuable members.

Before receiving her Climatact in the Alabasta Arc, Nami's fighting style was much more deceitful, using her brilliant mind and her good looks to solve her problems. She would shamelessly manipulate one of her crewmates to fight in her place, usually by blackmailing Zoro, charming Sanji, or ordering Luffy around. In the fifth One Piece movie she is even seen posing seductively to get information out of a bartender. She also had excellent luck: situations would arise that kept her out of the line of battles during fights. In a few rare cases, she'd used her looks to distract an opponent from attacking her. Her more manipulative battle-strategies began diminishing during the Alabasta Arc and beyond when she received her Clima-Tact and began to fight her own battles.

Some common techniques include Thunderbolt Tempo/Tempest (using Heat and Cool Balls, a cloud is formed, and by sending a Thunder Ball in, a huge bolt of lightning is summoned) and Mirage Tempo/Tempest (by manipulating the heat of the surrounding, Nami can create illusory copies of herself, which is further augmented by the Perfect Clima Tact's Mirage Tempo Fata Morgana).

I find it touching everytime Luffy entrusts his precious treasure (straw hat) to Nami whenever she is in trouble. First time he gave it to her was in her homeland when she asks him for help and he is like "DAMN STRAIGHT I WILL".   She understands the meaning of his hat. And once or twice she has to sew it up for him because the enemies try to rip it up.