is a Japanese manga series written and illustrated by Riyoko Ikeda. It was adapted into an anime series that aired on the channel NHK-BS2 from July 14, 1991, to May 31, 1992.

The series originally started out as a manga in the early to mid-1970s. The story is about a 16-year-old girl, , who attends a prestigious academy and deals with life as a high school student via writing letters to her "brother". The manga has been translated into French, Italian and Polish. The series spans 39 anime episodes and three manga volumes, ending when Nanako is eighteen.

Plot Nanako Misonoo is a young high school freshman at the exclusive girls' school Seiran Academy. When she begins her first year at this school, she falls into a world of female rivalry, love, chaos, and heartbreak. She narrates the story of the series in a chain of letters to a young man named Takehiko Henmi, who she calls "Oniisama" (Brother). In reality, Takehiko was her teacher at the cram school she went to earlier. She feels such a strong bond with Takehiko that she asks to continue corresponding with him. Takehiko agrees, and soon Nanako begins addressing him as "brother" in her letters. When Nanako starts her new school year at the all-girl Seiran Academy, she is unexpectedly inducted into the school's Sorority despite having none of the looks, talents, or background needed to become a member. As the series progresses, she becomes involved in the lives of the "Magnificent Three", the three most popular girls in the school.

As Nanako interacts with these ladies, she becomes attached to the great but troubled Rei Asaka, whom she wants to help, but cannot get close to due to Rei's obsession with Fukiko Ichinomiya, the Sorority president. Nanako also becomes friends with a beautiful and lonely young girl named Mariko Shinobu, who is determined to get into the Sorority and make Nanako her best friend at all costs. Meanwhile, Nanako has problems of her own; she is constantly being bullied by her peers due to her unlikely membership in the Sorority, especially by one Aya Misaki who feels that she should have been the one chosen for it. Throughout these problems Nanako is supported by her childhood friend Tomoko, the athletic but secretly ailing Kaoru Orihara, the passionate and troubled Mariko Shinobu and the correspondence with her "brother", who just happens to have some secrets of his own. The series chronicles her first year at Seiran Academy as she uncovers the past of some of the most popular girls in school, learning of love, loss, and her own family's secrets, including her true relationship with Takehiko.

Characters

The main character of the story, Nanako Misonoo is suddenly and unexpectedly chosen to join The Sorority, an elite group at her new high school, eliciting the wrath and jealousy of her classmates. Like many shōjo heroines, Nanako is innocent, caring, sometimes insecure, but always determined to do what is right. She begins the story hoping only to be liked by her peers, but is soon dragged into the lives and secrets of Seiran Academy's most elite students. She falls in love with Rei "Saint-Juste" Asaka, and their relationship is one of the major driving plots of the series.

Tomoko is Nanako's childhood friend and arguably the only "normal-themed" character in the series. In the manga, Mariko manipulates her into ending her friendship with Nanako, which Tomoko later rekindles when she realizes the misunderstanding. In the anime, Mariko attempts to end the friendship too and almost succeeds, but Tomoko ultimately remains by Nanako's side and protects her from Aya Misaki's bullying, and the three of them become best friends for the entire duration of the show, with Tomoko acting as the series' main comedic relief.

Rei "Saint-Juste of the Flowers" Asaka is a second year student and one of the "Magnificent Three" known for her social indifference and her many artistic talents, especially artistic (she plays the guitar and sings in the manga, and plays the piano, the flute and violin and acts in the anime). She is also shown playing basketball in the anime, replacing Kaoru in at least one game (Episode 16 "Comeback"). Incredibly loyal and devoted to the ones she loves, Rei's destructive relationship with Fukiko Ichinomiya leads her to be troubled, obsessed with death, and drug-addicted. She is Kaoru's best friend, with them exchanging playful insults at times and loyally helping each other at others, and shows a soft spot for Nanako when they interact, but her relationship with Fukiko prevents her from comfortably maintaining other friendships. The secrets between the two, and Nanako's involvement in them, is one of the major driving plots of the series. She dies late in the series; in the manga she dies by suicide via pill overdose, but in the anime her death is an accident as she falls off of a commuter bridge, into the path of a train (Episode 34 "Ablution"). She does this while trying to catch a bouquet of flowers that she purchased for Nanako, which she accidentally drops. In the anime her death deeply influences the other characters, as Kaoru begins to have suicidal feelings and the Ichinomiya family feel guilty for not doing anything for her, despite their wealth and their relationship to her. Ironically, Rei is the only one allowed, and who has ever seen Fukiko cry (Episode 25 "The Scarlet Lipstick"). Rei's nickname comes from Louis de Saint-Just, a French Revolutionary, known as the "Angel of Death".

Nanako's classmate, a fellow Sorority member and a former student of the junior high school attached to Seiran, Mariko becomes one of Nanako's best friends. Mariko distrusts all men because of her troubled family life: her father Hikawa is an erotica author who has an affair with an actress and later divorces Mariko's mother Hisako, who keeps her sadness bottled up as she raises Mariko practically on her own. As a result she is terrified of abandonment to the point where she becomes obsessed with the ones around her. She is also extremely beautiful, with red lips and long black hair as well as a curvy body, and shows an odd mix of vanity about her good looks and lack of regard for her own health if upset. On one occasion, Mariko becomes extremely possessive towards Nanako when Nanako tries to leave the Shinobu Residence. This later leads to Mariko refusing to eat until Nanako accepts her apology and forgives her. She collapses after three days due to hunger, before returning to eating as normal once the two friends have resolved the situation.. Mariko greatly admires Kaoru due to her strength and the emotional support she gives her as well, and at some point she admits to loving Karou (Episode 16"Comeback"). She also has odd interactions with Fukiko's brother Takashi, especially in the anime where she comically insults him (Episode 21). Almost at the end, Mariko injures Aya after Aya makes fun of her family problems in front of the class, leading Mariko to be suspended from school and expelled from the Sorority, which partially triggers the call for the Sorority to be abolished after Nanako declares that Fukiko's judgement on Mariko was too harsh, as she did not hear Mariko's side of the story. In the anime Mariko eventually comes to terms with her rivalry with Aya, realising they were both lonely and self-centred. Near the end of the series, Mariko's parents finally divorce. At first Mariko is extremely distraught, and reminisces about how her father was never there for her on her birthday, and Nanako observes how difficult it must be for her to choose a parent to live with as she loves both of them deeply. Furthermore, she feels shame about her father's profession deepens her self-loathing. After the incident with Aya and Mariko's expulsion from the Sorority, her father tells her that he believes there is good in everyone, including himself and Mariko, so she should love herself. She is able to resolve her feelings of shame towards her father's profession when Takashi hands her an old novel by her father, which is a sincere novel about his love towards his mother and his belief to live life in a way that will not be regretted.

"Kaoru-no-Kimi" ("Prince Kaoru") Orihara is one of the "Magnificent Three", the class representative of Nanako and her friend's class and the star of the basketball team, known for her tomboyish way of dress and her great athletic skills. She has a mysterious and deadly illness (breast cancer) kept secret from most of her classmates; it's only known in public that she was held back a year due to unnamed health problems. As Rei's best friend, she greatly dislikes Fukiko for everything she has done to Rei and hates the very existence of the Sorority. She spends the series trying to live her life to the fullest in spite of her disease, and is the one who supports Nanako the most when she is bullied, and helps Rei when she gets into major trouble. She was romantically involved with Nanako's "brother", Takehiko Henmi, but broke it off after her mastectomy. However, both Kaoru and Takehiko still have strong feelings for each other near the end of the series. Fukiko, who is also in love with Takehiko, encourages Kaoru to take up their relationship again after Rei's death, pointing out that Rei lived her life to the fullest until the last day, so she should too. In both anime and manga Kaoru marries Takehiko and emigrates to Germany with him. In the anime, she recovers from her cancer and gives birth to a child at the end of the series, but in the manga she dies two years after she and Takehiko leave. Kaoru's nickname comes from the anti-hero character, Kaoru Genji, of The Tale of Genji.

One of the "Magnificent Three", Fukiko "Miya-sama" ("Princess") Ichinomiya is a senior year student, the Student Council President, leader of the Sorority Club, member of the flower arrangement and horse riding club, and known for her elegance and dignity. She appears to be calm and generous, but is cruel and manipulative, often psychologically and physically torturing Rei for several ambiguous reasons, such as her desire that Rei should only have eyes for her and no one else. It is also revealed that she and Rei are full sisters, daughters of the Ichinomiya leader and a maid of the family mansion, although she was adopted by the Ichinomiya family and Rei was not. The annual Sorority candidate selections always cause extreme fighting and jealousy among the lower-classmen, which she promotes, believing that in competition one finds strength, so Fukiko sponsors Nanako's entry into the Sorority due to secret and ulterior motives: she is in love with Takehiko, does not know that Takehiko is really Nanako's stepbrother and confidant, and sees Nanako as a potential obstacle. She jealously tries to destroy their relationship by making Nanako love her instead (she believes that Nanako is writing to Hemni with romantic intentions and tries to make her stop writing him letters). In the anime, her love for Takehiko is given a backstory: she met and fell in love with him when she was twelve and he spent several days with her in the Ichinomiya mansion, but he unknowingly broke her heart by not showing up to her birthday party, which she had prepared a violin piece for, which emotionally splintered young Fukiko; Fukiko has since been stuck in that sense of love that she felt when she was twelve. Her room from that period remains the same as it was on the very day that she met Henmi (Episode 22 "A Summer Serenade"). In the end, she is able to overcome her childhood love and move forward, and in the anime she greatly laments Rei's death.