The Protagonist of this story. She is a 16 year old young girl from a middle class background who manages to be accepted in Seiran High, a very prestigious all-girls school, and then is a candidate to come into the high-class group named the Sorority.
A-Cup Angst: Though it only really comes up when she compares herself with the quite curvier Mariko
Team Mom: Once in a while comes as this, specially when Kaoru has a fit of pain and Nanako first gets her medicines, then takes care of her. (And slapping Rei for not really helping her at first, too.)
Tragic Keepsake: Two, and both are from the dead Rei: One of her cigarettes (which Nanako smokes when alone in her room), and Rei's favorite doll which is given to her either by Fukiko (anime) or Rei herself before dying (manga).
Good Parents: It's clear that they love Nanako and try to raise her as lovingly as they can.
Parents as People: ... Though both of them hide Takehiko's existence to Nanako, and later Mrs. Misonoo asks Takehiko to not reveal their true bond to her either. (In their defense, though, they didn't fully abandon Takehiko after his mother's death, with both of them gathering and then sending him the money he needed until he could fend off by himself, in addition to sustaining themselves and little!Nanako).
Your Cheating Heart: The Prof. turned to drinking when his first wife left him and took their kid (Takehiko) away with her, and it was during these days that he met Nanako's mom (the beautiful waitress of his favorite pub) and fell for her. However, the letter that demanded Nanako's ousting from the Sorority accused the second Mrs. Misonoo of being a homewrecker, which she obviously wasn't.
Nanako's former tutor, who helped her to get into Seiran. Nanako writes letter to him to tell her how her highschool life is, and refers to him as "Oniisama" ("Older brother"). He is actually the son of Professor Misonoo, from a former marriage. (Hence why the different surname, with "Henmi" being Takehiko's mom's maiden name.) Therefore he is Nanako's older brother, sorta. Unlike Nanako, he knows about their relationship; however, he hasn't been in direct contact with the Professor for several years, despite the death of his mother some years after the (rather bitter) divorce process, and how both the Prof. and Nanako's mom secretly provided young Takehiko with the money needed for his expenses until he could support himself.
Also, once in a while she might be seen biting on her thumbnail when nervous or angry.
Cry Cute: When Kaoru tells her she's okay and thanks her for her support. Aw.
Dark and Troubled Past - Parent with New Paramour: Her father not only writes porn novels, but later he leaves Mariko and her mom for the actress he was dating on the side. Needless to say, it has an horrible effect on poor Mariko.
Precision F-Strike: When Aya harrasses her and Nanako in public, Mariko lets out a rather epic "bitches like you don't know when to quit!" Also, when explaining who Aya is to Nanako a little earlier, Mariko openly refers to her as "that bitch".
Yandere: Very, very possessive of Nanako, to the point of trying to destroy her friendship with Tomoko, then threatening to kill Nanako. Unlike other Yanderes, when she does realise that this is not the way to get Nanako's affections, Mariko tones this side down and mostly evolves into a Tsundere, until she totally cracks when her parents definitely split up.
Younger than She Looks: With her ruby-red lips and Raven Hair, Ivory Skin features, 16-year-old Mariko looks at least 18. Lampshaded twice: when she and Nanako take a bath together and Nanako notices that Mariko is very curvaceous compared to her; and when, in the fair episode, Takashi directly asks Mariko "what, are you really sixteen?!"
The daughter of a former Seiran student who also was in the Sorority and of a famous lawyer, Aya is another Sorority candidate and Mariko's rival since junior high. Once she doesn't get chosen to join such an elite group, she starts attacking Nanako and Mariko mercilessly...
Too Dumb to Live: Aya's supreme arrogance and belief that she can pull a Karma Houdini on everything due to her social status get her physically (by either Mariko or Kaoru) or verbally (in the anime, by Tomoko and once by Fukiko) bitchslapped more than once. Specially when she taunts her rival Mariko due to her horrible home life - after pressing the already unstable Mariko's biggest Berserk Buttonto the freaking bottom, she gets slashed by her boxcutter in public.
Voiced by: Mayumi Setou
A junior Sorority member, who came in alongside Nanako and Mariko. Episode 15 of the anime focuses on her and her issues.
The Bus Came Back: Isn't seen a lot after her episode, but reappears in the anime rendition of the "Sorority disolution" arc.
Chekhov's Gunman: In the anime we get to see her in episode 11, where she and one of her friends wonder to themselves if it's true that Fukiko singlehandedly decided to get Nanako in the Sorority in front of a peeved Mariko. Cue episode 15...
Aya Misaki's Girl Posse, and apparently the only friends she has in school. Megumi has short hair and a somewhat deeper voice than other girls, while Miyuki has pigtails and acts a little more childish. They only appear in the anime.
The leader of the very exclusive Sorority and daughter to the very rich and noble Ichinomiya family, as well as one of the "Magnificent Three" of Seiran alongside Rei and Kaoru. Very composed and calm and a born leaderess, but with a far more complicated mind.
Berserk Button: You should neither make any allusions (even if accidental) towards her onesided love for Takehiko, nor speak openly against anything related to the Sorority. Expect some huge retribution if you do.
Flower Motifs: Roses, specially red ones. She sometimes wears a long black skirt with a red rose pattern, often walks through a garden full of roses, and people who want to win her favor try to give her rose bouquets ( In episode 15, Junko does it and fails when Fukiko gets her expelled from the Sorority, and Mariko tells Nanako to bring her some when Fukiko gets angry over Nanako defending Junko.)
Keigo: Fukiko is an extremely polite speaker and tends to use this, alongside the very formal watakushi as her personal pronoun. She almost never drops this, save from the time Rei pressed her Berserk Button in her birthday party.
Passionate Sports Girl: Subverted. While she is an excellent horse rider and a pretty good swimmer, this is used more as a way to empathize her Ojou background than to show her as a sportswoman.
Passive-Aggressive Kombat and Sugary Malice: Two of her specialities. Even at her angriest, Fukiko almost never openly berates her target directly and more often than not she speaks in a soft and gentle voice, but her venomous words can pretty much pierce your psyche to the bottom.
Precision F-Strike: A magnificent, overblown, and veryhammy "You shameless BITCH!" , towards Rei, during her BSOD in the birthday party. Made even more notorious by how Fukiko speaks very formally most of the time.
Room Full of Crazy: One in her Big Fancy House, full of Creepy Dolls and memorabilia of her time spent with her crush Takehiko — to the point of forbidding anybody save for a single cleaning maid to enter said room, where she has obsessively arranged the items and left them unchanged for six years.
The second of the "Magnificent Three", Kaoru is also the most tomboyish and levelheaded. She and Rei have been friends since middle school times, and loathes Fukiko for her treatment of her. She takes a Cool Big Sis role for Nanako, Mariko and Tomoko, as she is the Class Representative to Nanako and Mariko's class (due to some undefined health problems she had to be Held Back In School for a year, thus she's a junior despite being older than the rest). Also has romantic ties to Takehiko, and a huge secret in regards to her real health issues.
Berserk Button: She has two. First, don't bully someone in front of her. Second, please don't neglect your own health.
Bully Hunter: Very, very protective of Rei and Nanako. The third episode has her physically mauling Aya and her Girl Posse when they start bullying Nanako in class, and she also stands up to Fukiko several times for the sake of Rei.
Ill Girl: The exact reason why she was held back, though it's not known what she has. It's still serious enough to make her collapse in intense physical pain once in a while, often in VERY crucial moments. It's only explained at the end... Kaoru has breast cancer, and in fact, she had to go through a mastectomy at age 15.
Passionate Sports Girl: A member of the school's basketball team and a very talented athlete. And when she suffers an injury to her chest in the middle of a basketball game and is unable to play fully due to her illness, Rei takes Kaoru's place.
The third member of the "Magnificent Three", a beautiful artist/musician/actress and former basketball player. After she helps Nanako in her first day at school, Nanako attempts to help and befriend her but it'll be very complicated. Specially due to her drug addiction... and her very convoluted relationship with her older half-sister, Fukiko.
It's not even the first time she's attempted it. At some point Kaoru takes her bracelet by force and this reveals a scar on Rei's wrist, coming from her slitting it open in the past.
In episode 12, she reveals that she and Fukiko made a Suicide Pact of sorts (and that's where the scar comes from), and under the influence of a fever and drugs she tries to fulfill it... with Nanako. She barely stops once she realizes that she was about to Kick The Wrong Dog, and collapses in tears.
Also, in the anime there's a subversion. Rei's death is a genuine accident (she fell in the path of a train while in her way to a meeting/date with Nanako), but almost everyone except for Kaoru believes that Rei killed herself; the police later dispell this, when a boy who witnessed the accident tells them what truly went on.
Lonely Doll Girl: We don't see her carrying dolls around, but the only "company" of sorts that she has in her apartment is her porcelain doll "Poupee-chan". Which doubles as a Tragic Keepsake as it's a gift from her abusive half-sister Fukiko, whom she's obsessively in love with.
Meaningful Name: Her nickname comes from Louis de Saint Juste, a political leader from The French Revolution. A beautiful man who went through quite the heartbreak, threw himself in politics like Rei embraced sports, music and drugs, and also met a tragic end. (Though he was guillotined instead of killing himself/dying in an accident.)
Murder Suicide: She tries to do this (while being sick and drugged) on Nanako, whom she mistakes for Fukiko and then tries to perform her old Suicide Pact with. It takes Nanako's desperate words to stop this, and she collapses in tears.
Passionate Sports Girl: In the past, she was in the school's basketball team, but she has stopped playing. The reasons vary in each continuity: in the anime Fukiko forbids her from playing basketball again, but in the manga she quits playing of her own accord. At some point she takes Kaoru's place when Kaoru suffers an injury to her chest during an important basketball game, and we see that her playing skills have not decayed at all.
A high-ranked lady from the Sorority, and a close friend of "Lady Mona Lisa" Komabayashi. In the anime it's explained that she has always been deathly jealous of Fukiko, and tries to upstage her. The results are... a complete disaster.
Another high-ranked Sorority girl, called Mona Lisa due to having a mysterious smile and dark black hair like the famous painting. "Lady Borgia" Ogiwara is her closest friend. She actually confronts Nanako about her and Fukiko's deals first. Later she and Ogiwara team up...
Number Two: Said to be this to Fukiko in the manga.
Not So Stoic: In the anime. When Ogiwara corners Nanako and almost tosses her off a balcony and into the river (unintentionally, as she only wanted to know more about her and Fukiko but didn't plan to harm Nanako seriously), Komabayashi has a huge breakdown. She saves Nanako and then collapses in tears, begging Ogiwara to stop and hugging her.
"Lady Medusa" Katsuragi
Voiced by: Kumiko Takizawa
Another high-ranked Sorority girl, and the one that Fukiko is in best terms with.
Messy Hair: Which is the cause of her "Medusa" nickname.
Number Two: Apparently, to Fukiko. Komabayashi is mentioned to be this, but Katsuragi seems to be personally closer to her.
"Lady Cattleya" Yamamoto
Voiced by: Satoko Yasunaga
Another high-ranked Sorority girl, she seems to get along well with the younger members. She and "Vampanella" Hoshino also seem to be close friends.
Uncle Pennybags: Doesn't mind giving Takehiko rides in his Cool Car, spends a good part of his wealth on treating his friends, and ultimately pays for everything in Kaoru and Takehiko's wedding so they will be happy.
Amazingly Embarrassing Parents: One of the few cases when this trope is NOT Played for Laughs. Hikawa is not just any kind of writer, but a writer of erotic novels: while he donates quite the money to the Seiran campus, Mariko is looked down on by other students for being "the daughter of a pornographer". According to Aya everyone knew but just chose not to say anything, and she openly uses it to bash Mariko as a person.
Ascended Extra: In the manga Hisako was seen in two scenes, and Hikawa only was alluded to. They gain some more spotlight in the anime, and specially in episode 29.
Cooldown Hug: Hisako gives one to Mariko, when in episode 29 she tries to throw herself off her balcony in her Heroic BSOD state.
Parents as People: They're not bad persons, but they have issues. Extremely severe issues. Hikawa is very distant due to his work and his affairs, Hisako is very kind but veers dangerously into Stepford Smiler.
Rags to Riches: According to Mariko, Hikawa and Hisako were very poor when they got married, and then got progressively richer as Hikawa's novelist career flourished. (Though at the cost of them growing apart, as well as Hikawa resorting to write his succesful erotica rather than the more meaningful literature he was fond of.)
Tragic Dream: Almost at the end of the series, Mariko tells Nanako that she learned about her parents's past. She says that Hikawa wanted to become a great novelist and had genuine talent, but now writes erotica because that's what sells. Back then he actually wrote a really good and beautiful novel, but it was a fluke; Mariko finds a copy of it and says it's technically great.
Your Cheating Heart: Hikawa first cheated on Hisako, then left her for a beautiful redheaded actress. They get officially divorced in the last third of the manga/anime... and the consequences are HUGE.