Nabiki Tendo (天道 なびき Tendō Nabiki?) is the middle daughter of Soun Tendo, making her the younger sister of Kasumi and the older sister of the female protagonist, Akane. Her first name comes from the Japanese word nabiku, which means "to bend, yield, or sway to." Tendo means "the laws of heaven and nature."
Nabiki has chin-length hair (brown in the anime) that she wears in a bob cut. As the middle sister, she is midway in height between her sisters, which also characterises her personal style. Aside from the Furinkan High School uniform for female students, she tends to wear a tank top and shirt with shorts or sweater and jeans at home. Nabiki has a more extravagant sense of fashion than either Akane or Kasumi, although it is revealed that she also borrows Akane's clothes. She is frequently depicted in the manga wearing costumes drafted by Erté.
Nabiki is the middle of the three Tendo sisters and is a second year student at Furinkan High School. Even at her young age, she is gifted at methodically serving her own interests at the expense of anyone else, including her family, and has no compunctions against emotionally wrecking, manipulating, tormenting, impoverishing or setting up others in life-threatening situations for either money, amusement or petty pride, even if she owes them her life several times over. She encouraged Kuno to keep his infatuation with female Ranma and Akane to further her regular sales of clandestinely-taken photos, which he keeps in a large album. She also regularly uses incrimination or blackmail to get what she wants. In the anime she has also taken bets on Ranma's fights.
While she comes from a martial arts school, Nabiki is not a combatant. Although she always keeps her wits about her, she has herself stated that she's a completely untalented fighter. The only fighting skill she has shown is clobbering Kuno unconscious with a small mallet from behind, while the latter was completely distracted, although Akane also performed the same feat just previously. She has also occasionally manifested a variant of the standardised intimidating battle aura that is recurrently used by various characters for comedic effect, but like Kasumi, and unlike her father, it hasn't been shown as useful for anything else, and is only workable when she's thoroughly mad/furious. She generally ensures that the violence around her finds other targets to occupy its attention, although she mis-planned, and briefly found herself defenseless, when Shampoo and Kodachi decided to simply kill her.
Though she is usually shown as unconcerned about other people, and has been outright stated to have 'no maidenly feelings' , Nabiki was the one who displayed the most initial interest in Ranma when her father announced the pending arrival of a well-travelled guy.
She hoped he was cute and was initially pleased with what she saw. It was not until she learned the pigtailed martial artist turned into a girl that she changed her mind. She's been portrayed in her general character since her interactions with Kuno a few chapters later.
Nabiki has been shown to be observant, curious, resourceful and cool under pressure. But also as sadistic, petty, sarcastic, manipulative, contemptuous, impatient, extremely greedy, irresponsible/wont to foist her blame onto others, nearly barren of conscience or compassion and completely amoral, but seems to be childish at times, and is very fond of all types of tasty treats, including junk food. She has shown no compunctions about severely betraying her family, or cheerfully and extensively tormenting someone who's just saved her own life twice over. She has also taken advantage of the situation her family finds themselves in with the embattled engagement between Ranma Saotome and her sister Akane.
Nabiki is eminently fond of money. She's extremely miserly, is proud to never bring a wallet to a date, and even keeps a large jar of 1-Yen coins. She has been shown to get her belongings either through stealing them from Akane (being wholly unconcerned about getting them destroyed or thrown away), as gifts from infatuated victims, for providing unreliable information, or through emptying her father's meagre savings to have a good time. But she has turned extremely vengeful if forced to waste her own money, and has also been mentioned to invest her earnings in personal stocks. She has taken advantage of Ranma's comparatively honest, straightforward nature and his moral 'inhibitions' for an effortless income source, such as regularly selling revealing or semi-revealing photographs of girl Ranma(Set of five for 3000/5000 yen!) to many of her schoolmates, taking world-wide orders for above-themed handkerchief prints, attempting to use him as a servant, or generally swindling him. Her love of money frequently leads her to betray her family to gain more of it, and she's been more than willing to ruin them to win a bet, or destroy her sister's wedding to get presents. She's been shown as completely indifferent to the plights she puts them through. However, she will occasionally work together with her family, such as revealing the Gambling King's bad habits in order to win back their shared living space, i.e: the house, though she initially helped the latter in his endeavours to swindle kindergarten children of their money.
She has been shown as entertained by the insanity and supernatural chaos surrounding Ranma, and interested in the romantic (or otherwise) entanglements he and Akane get involved in, despite repeatedly expressing an extremely low esteem of his character.
She will occasionally set up dangerous, or potentially life-threatening situations for simple amusement, like informing all his paramours that he was going to give Akane an engagement ring, even without profit involved, just to watch the spectacle when he's beaten up, and destroying Nodoka's/the Saotome family's house in the process, using him as a human shield against an attack from his paramours and initially planning to continue doing so in the long run, or lying to her father that he's fallen in love with Kuno to provoke an attack. However, she's been contemptuous and annoyed when this has involved her father making a public spectacle of himself, pretending not to know him.
Her intelligence and talent for manipulation has helped her to mostly use less refined characters to personal advantage without any negative accountability. Whenever she deals with Ranma, for example, she's bluffed or threatened to blackmail him, if her frauds, manipulations or other schemes have angered him ('Hurt me and everyone will get the photograph').
She once feigned love for him, since she found it entertaining to play with his and Akane's emotions, and cheerfully tormented them with extended hardships, including inadvertently re-establishing the morning attacks on her sister by spreading newsletters, auctioning Ranma's services, letting him take damage in defence of her, using their compassion against them by feigning heartbreak, and having fun with the tension from Akane's paranoia and the couple's flustered insecurities about their relationship. At one point, Kasumi remarked to her father that Nabiki told her that she planned to sell the dojo for a life of leisure,
It seemed Nabiki's real plan was to sell Ranma back to Akane permanently, but Akane refused to pay Nabiki anything even when Nabiki severely lowered the price on several occasions. After Ranma and Akane got into another fight, even Nabiki worried they had broken up for good and that she took things too far 
Nabiki has shown expert acting skills, being able to easily fake tears or make utterly convincing expressions, and even use ventriloquism to imitate another voice. She's effortlessly kept up a straight-faced over-dramatic play-act about feigned love even while in free-fall from a helicopter, simultaneously allowing a rival swindler to fall after refusing to pay her in exchange for a working parachute (she sabotaged the one he was wearing). She kept up the act even as he lay dying in a crater on the ground, and only briefly let up a triumphant grin while using his money to call an ambulance to win the competition, to instantly effortlessly switch back to the unflinching theatrics. Afterwards, she was depressed and genuinely weeping, but the stated reason was not lost love, but rather regret for not making their bet concern 10,000 Yen instead of 10 Yen.
Although Nabiki has been shown with a personal social circle, certain other regular cast members have stated a dislike due to her conscience-free and duplicitous nature. Ukyo has attacked her together with Shampoo and Kodachi, and the latter two intended to kill her.
She's deliberately appealed to or created a demand in potential customers, such as encouraging Tatewaki Kuno to keep his infatuation for Akane and the "pigtailed girl" in the first manga chapters (she instantly had pre-prepared pictures of both ready for sale, implying that she thrived from encouraging the attacks on her sister just previously), to consistently sell him semi-revealing photographs, though she's sold collections of Ranma-chan to a queue of other schoolmates as well. Among other things, she has auctioned Ranma to the school's many sports clubs to help fill out their teams, and been willing to transfer her engagement to Ukyo and Kodachi for 6350 Yen.
Nabiki also indifferently framed him for assault as an eternal blackmail source out of annoyance for him accidentally destroying her concert ticker, until he destroyed the 'evidence'. When she cheerfully ran up a huge gambling debt during her battle with Kinnosuke Kasha-Oh, she also seemingly sold girl Ranma as a waitress, dragged away by a neck-chain, to a casino to help work off her gambling debt, and was completely blasé/at best mildly curious after the latter managed to escape from his captors.
She's shown no business ethics whatsoever. She has taken the principal's money and ran from the taken assignment, repeatedly lied about non-working solutions ('Money first!'), and left Ranma pay her food tab despite just promising that she'd treat him. Another notable incident showed her taking advantage of an amnesiac Kuno by convincing him that he owed her 5,000 yen, which she instantly regretted only for not making it 10,000. She's also unashamedly told Ranma to catch and beat up a 'stalker' in exchange for one of her 5,000 Yen picture sets of his female form, which she's never been shown to let him/her get a quota from. She's made a claim that, despite not having any talent in the martial arts, she has pride in her legacy and won't refuse a challenge, but instantly dumped the assignment on Ranma. The only signs of 'honour'/petty pride she's displayed was a burning need for vengeance due to being outsmarted/"taken advantage of", and when accidentally forced to waste her own money, but in both cases endeavoured to inflict vastly greater amounts of 'payback'.
Nabiki's mischievous nature is referenced by a manga splash page depicting her wearing a demon suit in opposition to her elder sister Kasumi's angel. Although when Ranma severely manipulated Akane's feelings to make her give up a "battle-dougi" (since it boosted her fighting skills beyond his own), and the latter responded with love and acceptance, he felt like scum, which was visibly shown in a similar symbolic manner.
There is a marked contrast in character between the two sisters. They are frequently used as two diametrical 'cynical'/'considerate' perspectives on the antics surrounding them. Nabiki has been referred to as 'have no maidenly heart' by the narrator during the intro of the Kasha-Oh arc, and two stories have been devoted to dealing with Kasumi's lack of 'negative' instincts, the former placed right before Nabiki's lengthy competition with Kinnosuke Kasha-Oh. Kasumi has been able to see through her schemes, but like her father has been extremely forgiving, and at most vainly tried to convince her otherwise. Although she made a careful balance-tipping choice comment to their father when the latter was about to accept Nabiki's and Ranma's engagement at the expense of the flustered Akane.
Akane is shown to generally wish to believe the best of Nabiki, despite all evidence to the contrary, and shows disappointment from her sister's betrayals. Nabiki has expressed at least a modicum of respect towards the latter, as she's stated that she considers Akane tougher than herself, but Kasumi has also mentioned that they've had a tendency to fight a lot. In contrast to Akane, Ranma is more suspicious of her motives, frustrated with being repeatedly cheated and abused as one of her tools. Although he's been bound not to retaliate, either by threat of blackmail, or his own ethical restraints, which prevent him from attacking those who cannot fight back. He views her as extremely greedy for casually selling him/her as a waitress, and then allowing Kinnosuke to fall without a parachute. Despite this, he remains willing to assist her even as she ruthlessly takes advantage of his compassion.
Her father has been mortified or broken when taking the brunt of her schemes, and through these situations she's the only daughter he's ever been shown to be openly upset with. Yet, he's never been shown to hold a grudge afterwards.
Despite her normal crafty behavior in the manga series, she has shown nostalgic and melancholy feelings for her dead mother. When Ranma was under the threat of obligatory suicide if he revealed himself to Nodoka, Nabiki initially tried to expose him out of jealousy. But for once, she relented and vowed to stay out of their way, simply telling him to speak to his mother while she was still around. Nabiki has consistently been shown as enthusiastic when Nodoka visits the family and calls her 'auntie Saotome. Nabiki was the most fiercely opposed to allowing the sloppy and ditzy, but well-intended and righteous Hinako to propose to Soun. But when the teacher bribed her with 10,000 Yen, she immediately relented and set them up on a date.
An odd tidbit is that she’s shown more upbeat attitude towards Ryoga than any other male, save perhaps her father, as she’s been enthusiastically interested in the former's love life with both Akane and Akari. She's been shown to enjoy eating the delicacies he brings her family from various visited regions, so perhaps the reliable source of free treats is the cause of this?
As a minutiae, Nabiki and Kasumi have not been shown as victims of Happosai's actions, though he enthusiastically attempted to peek on Nabiki early in the manga, when he thought she was naked in the bathhouse. Given Happosai's vast power, and utter ruthlessness when provoked it's uncertain to base this on fear. It's possible that this 'immunity' is granted because Kasumi is the only household member who regularly treats him with consideration, while Nabiki is simply too hard to tease or outsmart. She also does not appear to be energetic enough to keep his interest and tends to stay out of his way. Though they have not shown antagonism, given that he didn't mind offhandedly granting Nabiki's request to stop/knock out Ranma, when she was chasing the latter to find out why he wouldn't undo his pigtail (The reason being that it was kept in place by the supernatural hair-growth stopping 'Dragon's Whisker'). In an instance from the separate anime continuity, Kasumi has a battle aura surrounding her because of Happosai's actions, while Nabiki simply punches him away.
In the anime, Nabiki has generally been more compassionate. She has shown a soft side for her sister in "Tendo Family Goes to the Amusement Park!", and was also genuinely distressed at Kasumi's possession and her father's willingness to sacrifice his life during "The Evil Ogre! Hell Hath No Fury Like Kasumi Scorned." Most of her harsher moments such as auctioning off Ranma did not appear in the animated adaptation.
She narrates the compilation episode, Tendo Family's Annoying Acquaintances!. A reason for her miserly ways are provided, with all the jobless lodgers at the Tendo home, Soun Tendo has little money to give to Nabiki. Along with this, Ranma's tendency to inadvertently disturb the peace of the Tendo house(such as causing a mob of people to crash into her bath in the short) annoys her. Nabiki felt there was something suspicious about P-chan's behavior.
Nabiki has been stated to not possess any 'maidenly feelings', or 'be completely heartless' in the initial author notes of the Kasha-Oh story-arc, depending on the translation. She has used her classy and attractive appearance to fleece and swindle any potential suitors for all they are worth, conning them into giving her expensive food, clothes and jewellery. At the point she's gauged that they've reached their financial limit, she immediately breaks up the relationship and blackmails them to pay her additional money afterwards by threatening to distribute their love-letters. Nabiki is very good at faking amorous emotions to fit her needs. She thinks it's amusing to repeatedly manipulate and abuse Ranma's feelings with sadistic play-acting. An (unsuccessful) rival swindler may have been another victim of this deception.
In the anime Nabiki and Kuno have been implied as a potential couple in the episode "Extra, Extra Read All About IT! Kuno and Nabiki!" where Kuno was told by a famous fortune teller named Gendo, on the basis of a fire reading that had been unintentionally sabotaged by Sasuke, that she was the love of his life. He started trying to forget about Akane and the pigtailed girl. Nabiki was amused by his affection, but didn't take him too seriously. When the fortune teller explained his mistake, Kuno stopped trying to force himself to love her (although he had already angered Nabiki, Akane and Ranma by declaring to the school that he would wed Nabiki and keep the other two girls as his mistresses after girl Ranma accused him of abandoning her).
Another implication sign of love was in the second movie where he attempted to save Nabiki but ended up needing her help, and in the OAV this was seen more often, such as in the OAV Oh, Cursed Tunnel of Lost Love! Let My Love Be Forever, Nabiki and Kuno managed to go through the cave without getting separated.
The manga also has a gag about the two in 'The Umbrella of Love!' story, when the two fell under the titular magic umbrella. Nabiki asked for 1000 Yen as proof his love and tearfully stated she'd treasure the money for the rest of her life, once the umbrella was removed Kuno was in shock, whilst Nabiki is annoyed she didn't ask for more money when under the magic umbrella.
Extraordinary attributes: Although Nabiki apparently keeps in shape enough to keep a lean figure despite her considerable love of food, at least some of it through light aerobics, she is one of the few prominent cast members without great superhuman physical power.
Nevertheless she occasionally displays her family's trademark giant battle-aura, and has demonstrated mildly superhuman speed and reflexes when barely dodging Ranma's high-speed grabbing while hidden from his sight behind a shrubbery. However, she has been vulnerable to even comparatively minor impacts, and was once knocked out through simply falling and hitting her head to the floor (although she recovered very quickly). She was claimed to have been severely threatened by unexpectedly plummeting from a second floor balcony, although she didn't seem the least bit frightened as she fell. She does possess sufficient striking-power to knock out Kuno through blunt weaponry when taking the latter completely by surprise from behind, so, given all of the above, her father may have provided Nabiki with regular martial arts training earlier in her life, even if she only trains through more regular activities within the span of the manga itself, but she has been stated outright as much less talented than Akane. Like for several other cast members, the mallet qualifies as the frequently demonstrated comedic feature to ´pop forth´ small items seemingly out of thin air (fan nickname: "hammerspace"), but only Happosai, Mousse, and perhaps Kodachi, Ryoga or Genma, have ever used it to more 'extreme'/notable extents.
In the manga Nabiki once used ventriloquism to speak through a wooden puppet belonging to Kinnosuke, possibly imitating the appropriate voice in the process.
Additionally, in the anime her self-control was shown as sufficient to create severe difficulties in reading her mind, and to overwhelm the telepathic child through intense personally selected imagery when she eventually allowed him access. (Tidal-waves of money, or visions of an implied erotic nature)
Talents: Nabiki's true strength lies in her cool head, iron nerves, high-speed adaptive scheming, efficient practical psychology, utterly convincing master actress skills, seething greed, pride, and spite, leading to a very entrepreneuring spirit, near absolute lack of ethical restraints, and some acquaintance with a multitude of areas such as forgery, worth evaluation, law, investment, and photography. She can efficiently multi-task different actions, steps or minor schemes simultaneously, with several back-ups along the way. However, she also tends to be sloppy, hedonistic, stick to mostly straightforward ideas, and generally plans as she goes along rather than in advance.
Miscellaneous: Near the end of the manga, Nabiki once helped Akane to grow spores from magic mushrooms, which could control age through digestion, but it is left to fan imagination if she continued to cultivate them for herself afterwards. Turning herself youthful again every 10 years is definitely something she would find useful, as would auctioning them off to billionaires. Given the frequent occurrences of useful magical items (handy temporary shapeshifting powders, potential permanent power-up waters, memory-erasing shampoo, magic herbs, a duplicate mirror, another for time-travel, etc), it can be seen as odd that such a greedy, pragmatic, and absolutely ruthless individual would not attempt to hoard a variety for herself, but given the episodic convenience of the series, everything must return mostly to normal by the end of each storyarc.
Nabiki is portrayed in the live action special by Maki Nishiyama and her character underwent the most changes in the adaptation. Although brown, her hairstyle is different as she no longer wears it in a bob cut. She also dresses differently. Notably, she is no longer a high school student but works at night at a hostess bar downtown which is frequented by Soun and Genma after the Saotomes arrive in Furinkan. She also takes a liking to Genma's panda form which she calls "Panada-chan", an aspect of their relationship that was not present in either the manga or anime.
- Nabiki makes a cameo appearance in episode 12 of the anime Maze.
- Nabiki's moneymaking ways and miserly heart are similar to Oyuki while her sadistic personality is similar to Ryoko Mendou, both from Rumiko Takahashi's first manga series, Urusei Yatsura.
- A character from Rin-ne, another of Rumiko Takahashi's works, named Kuromitsu bears a strong resemblance to her.
- In the anime, at least, Nabiki has two teens from her class who seem to be her friends and/or henchmen. They are supposedly named Kikuko and Ryonami. They can be seen as Nabiki's equivalent to the four girls who make up the best friends of her little sister, Akane Tendo.