The TV series premiered January 10, 2002 on TV Tokyo and finished in run on June 27, 2002, totaling 25 episodes. A New Year's special episode was included in the seventh DVD volume (KIBA-745) released on October 2 of the same year. Due to production schedules, the manga adaptation, illustrated by Azusa Kunihiro, started serialization in Akita Shoten's Shōnen Champion on November 8, 2001, two months before the anime premiere. The manga ended on May 25, 2002 and collected in three volumes.
The title Seven of Seven or Shichinin no Nana is a pun, as the main character's name, Nana, means 'seven' in Japanese. It relates the premise of the series, where Nana has split into seven different sides of the personality due to a slight accident from an experiment her grandfather was conducting. In addition, Nana Suzuki's voice is also done by another Nana, Nana Mizuki.
After seeing a rainbow as a child and being mesmerized by its beauty, Nana's grandfather has been trying all his life to capture the beauty of a rainbow within a crystallized form. After years of failed attempts and crazy inventions, such as a VCR toaster and vacuum cleaning mouse catcher, he finally discovers a way to make such a crystallized rainbow. His plan would work by separating the light from a rainbow into its seven basic colors and then reforming it into seven colorized crystals. His experiment was working too and only needed a few seconds in the microwave to be complete and finally fulfill his dream. That is when Nana, who was searching for the microwave in an attempt to bake a chocolate cake for Yuichi, opened the door before the crystal had fully hardened and caused an accident.
The crystal glowed and split into the seven colors of the rainbow, hitting Nana as one color and coming out of her in seven separate colors of the rainbow, creating seven different Nanas. Aspect of Nana's personality suddenly exist its own separate physical form, there is a giggly Nana, a sleepy Nana, a crybaby Nana, a slowpoke Nana, a grumpy Nana, one who is a bit of a flirt, and an intellectual Nana, who all standing alongside the original Nana. However, they are all also the same Nana, and all share the same feelings for the boy Yuichi, which is clearly seen as their first thought is to finally make that chocolate cake which they try to do and are working and talking in perfect sync with each other, as if they were still just one person, that is until the cake is done at which time they start fighting over who will give it to Yuichi.
Each Nana grabs one of the crystals that formed from the one crystal her Grandfather was trying to harden in the microwave and realizes it gives her super powers, she can fly, has super strength and super speed. This leads to a chase between the original Nana, and the new six sides of her personality who are all fighting as they fly and destroy parts of town over who will give the cake to Yuichi. When they finally finish, they once again prove they are all parts of the same Nana as they are all too scared to approach him and hand him the cake.
The crystals also hold another power seen later on as Nana wears a costume from an anime she (and the other Nanas) loved as a child called the "Nana Rangers". While they are wearing the costume and at the same time carrying their crystals the prop costumes turn into the real "Nana Rangers" costumes allowing them at times to be Superheroes, and also all show themselves in public at once, since Nana and the others realize the danger of all being seen at the same time without masks or some way of hiding that they are all the same person.
After they had settled on their roles, the 7 Nanas also face the fact that if the crystals are not reintegrated within a year after the split, all 7 of them will disappear. Later, the 8th one appears causing chaos.
- Nana Suzuki (鈴木 ナナ Suzuki Nana?) - Nana in her original form, and the one form that remains even when the other parts of her personality split from her. Shy and very timid, and for as long as she can remember she has had a crush on a boy in her class called Yuichi, and yet has been scared to approach him and tell him how she feels. This has led to three girls, that actually turn out to be her friends as the story progresses, to tease and torment her as they try to vie for Yuichi's attention. She is also the only Nana to be called only "Nana". Her color is Blue. Voiced by: Nana Mizuki (Japanese), Veronica Taylor (English)
- Nanappe (ナナっぺ Nanape?) - The "Hot tempered Nana". Quick to anger and a tomboy, she likes to fight and work out. Her color is Red. Voiced by: Sumomo Momomori (Japanese), Veronica Taylor (English)
- Nanakko (ナナっこ Nanako?) - The "Slow Nana". Laid-back, this Nana has an affinity for fish items (specifically, Billy-related items). Nanakko takes a relaxed approach to life, even with an approaching deadline, and speaks with a childish and congested voice. Her color is Orange. Voiced by: Madoka Akita (Japanese), Veronica Taylor (English)
- Nanacchi (ナナっち Nanachi?)- The "Happy Nana". Happy-go-lucky, she likes movies, especially funny ones. Her color is Yellow. Voiced by: Mai Asaki (Japanese), Veronica Taylor (English)
- Nanarin (ナナりん Nanarin?) - The "Sad Nana". She likes video games. Very sensitive, up to the point that almost anything can make her cry. Her power allows her to emit sonic waves from her voice when she cries. Her color is Chartreuse (called "Yellow-green" in the English dub). Voiced by: Yukari Fukui (Japanese), Veronica Taylor (English)
- Nanasama (ナナさま Nanasama?) - The "Intellectual Nana". Intelligent and stubborn, this Nana likes books and manga. The title of the book she always reads is Les Miserables. Her color is Green. Voiced by: Mai Nakahara (Japanese), Veronica Taylor (English)
- Nanapon (ナナぽん Nanapon?) - The "Sensitive Nana". Flirty and mysterious, she likes spiritual things. She also has the essence of feminine physique. At one time, she used her crystal to hypnotize many other people, and eventually herself while trying to teach the original Nana hypnosis. Her color is Purple. Voiced by: Kaori Nazuka (Japanese), Veronica Taylor (English)
- Jamanana (ジャマナナ Jamanana?) - The dark side of Nana or the "Eighth Nana". She first appears on New Year's, planning on interfering with Nana's plans. Unlike other clones, Hitomi cannot tell her apart from the others. While she, like the other Nanas, wants Nana to succeed, the Eighth Nana is not beyond using less moral methods and sabotage to ensure Nana's success. She has proven to be more powerful than the other six combined. Jamanana can hypnotize people, even without carrying her crystal. The black crystal that symbolizes her emerged when all seven Nanas were depressed over Yuichi's interest with Tsuki, and the crystal in the microwave oven was starting to break. As a Nana Ranger, Jamanana has white hair and wears a jagged red scarf, sharp ears, and inward curving horns on the helmet, and does not need a costume to transform. Her color is Black.
- Hitomi Onodera (小野寺瞳 Onodera Hitomi?) - Nana's closest and oldest friend, she tries to support Nana in her quest to tell Yuichi how she really feels. Her parents also own a restaurant which she and Nana go to each year and have a yearly party. She is also the one that seems to know Nana better than Nana knows herself, and can easily tell who is who after they split into seven individual parts of the same personality. Hitomi has completely different looking eyes without glasses, a feature Hitomi used to disguise herself. Voiced by: Miyu Matsuki (Japanese), Rachael Lillis (English)
- Yuichi Kamichika (神近優一 Kamichika Yuichi?) - Nana's crush, he is into photography and is continually taking pictures around town. He is also very smart and that is part of what scares Nana as she quietly tries to keep up with him in a way that will allow her to attend the same high school as him. Unfortunately, it may be that he's holding the torch for someone else. Usually kind and open, he comes to see Nana as a good friend, however he is completely oblivious to all the girls around him who have a crush on him. At the end, he finds out that Nana has a crush on him.Voiced by: Akira Ishida (Japanese), Michael Sinterniklaas (English)
- Mr. Handa (半田実 Handa Minoru?) - The vice-principal of Nana's school, he is really a nice guy underneath the gruff exterior, but also tries to push Nana and the other students very hard, as it turns out that it is mostly for their own good. He defends Nana when she is refused a chance to enter her chosen high school after the Eighth Nana hurts Tsuki, noting that while Nana was looked down upon by members of the honours class, she has since worked hard to become one of its top students and would not be so foolish as to throw it all away. Voiced by: (Japanese), Marc Thompson (English)
- Mr. Maruoka (丸岡雄之 Maruoka Takeyuki?) - Nana's guidance counselor, he is another one that is trying his hardest to help the students and is actually a good guy too, but also one that comes off as slightly gruff and often at odds with Nana. Hitomi has a bit of a crush on him because he put his jacket around her when she was cold during Christmas (Mr. Maruoka had no idea it was Hitomi), something she imagines her ideal boyfriend would do. Voiced by: (Japanese), Dan Green (English)
- Megumi Hayashiba (林葉めぐみ Hayashiba Megumi?), Erino Kogarashi (木枯えりの Kogarashi Erino?), and Motoko Morinuma (森沼もとこ Morinuma Motoko?) - Three girls in Nana's grade who initially tease and torment her, but soon see how hard Nana is working and will stand up for her when they think she deserves some credit and support her endeavours to get into high school. The three girls have the worst marks in school, but want to enter the same high school and are impressed that Nana managed to move from their level to the honours class with Yuichi and Hitomi. Hayashiba, the leader of the group, is a childhood friend of Nana's and a very talented Japanese dancer, Kogarashi is a sneaky girl who brags about people, and Morinuma is the girl with fish lips who wears baggy pants all the time and turns out to be kind and empathetic. Hayashiba eventually chose a Japanese dancing school, a different choice from Kogarashi and Morinuma, as a promise to her grandfather to become a maiko dancer. After the graduation, Morinuma went to a nursing school, Kogarashi entered a special school to became a cartoon voice actress.
- Mayor - Owner of the 7 of Seven convenience store. Mayor lent the Nana Ranger costumes to Rokuzo (Nana's grandfather) when Rokuzo claims he had found 7 girls working for school festival. After the Nana Rangers had saved Mayor from a scooter gang, he gave them the costumes as gift. Voiced by: (Japanese), Jimmy Zoppi (English)
- Tsukie Kayano (萱野月枝 Kayano Tsukie?) - A childhood friend of Yuichi and a seeming rival to Nana for his affections. She is currently in her last year at the junior high division of Yasaka Ōji and studies hard in obtain a good placement for when she moves to the high school division. Yuichi and Nana have both applied for the high school division, despite how difficult it will be to enter. Her focus on her schoolwork leads her to reject Yuichi's feelings for her and, after criticizing Nana for spending time doing things other than studying, gains the dislike of the trio of girls supporting Nana. Tsukie, brilliant and focused, is the reason why Yuichi is so smart - he wants to get into the same high school as her and studies as hard as he can, like Nana is attempting to do to stay with Yuichi. She loves art, but because members of her family have traditionally become doctors, she is expected to study medicine and go to university. After becoming friends with Nana, she decides to study art instead of medicine at her high school. Voiced by: Tomoko Kotani (Japanese), Bella Hudson (English)
- Rokuzo Suzuki (鈴木六造 Suzuki Rokuzo?) - Nana's grandfather, who lives with Nana. He spent a lot of time on his research and did not pay much attention to Nana, which resulted in the incident that splits Nana into seven. He does care a lot about her and worries that his experiment might have dire consequences on Nana's well being. Many of Rokuzo's experients have ended in failure, including attempts to recombine Nana. Voiced by: Mugihito (Japanese), Mike Pollock (English)
- Mitsuko Suzuki (鈴木みつ子 Suzuki Mitsuko?) - Nana's mother who lives in San Francisco for business reasons. She loves Nana dearly and wants her daughter to be as successful as possible. She and Yuichi run into each other in San Francisco without either of them knowing how the other is connected to Nana nor does Nana ever know her mother and Yuichi have met. Voiced by: Sumi Shimamoto
- Goro Suzuki (鈴木五郎 Suzuki Goro?) - Nana's father. He also lives in San Francisco. He is a bit of a pushover, but also loves Nana a lot. He is more sentimental than his wife, especially when he notices that both Nana and Grampa want to remain in their house in Kotomachi, but tends to go along with her wishes.
- Melody Honey (メロディー・ハニー?) (Miss Honey) - A girl from San Francisco sent to Nana's house to help Nana improve her English, though she turns out to be a complete slacker who does not really attempt to tutor Nana. It turns out that Nana's mother sent Honey to Japan so Honey would be able to confess her feelings to a boy she knows in Japan. During her visit, she discovers the secret of the seven Nanas, but promises to keep it a secret. Nana runs into her again in San Francisco, when it turns out she is Yuichi's host during his home stay program. Melody Honey is also a minor character in the anime Keroro Gunsou (Sgt.Frog) and in Arcade Gamer Fubuki.
- Mary - During Nana's trip to San Francisco, Honey assigned Mary, a little girl whom Honey babysits regularly, to Yuichi and Nana as part of the home stay program. Mary tried to use Nana's crystal, but she could only cause earthquakes.
- Billy - A fish mascot. It is usually seen as a fish pillow that Nanakko always carries. Billy also appears as other forms of merchandise, such as the keychain Nana gives Yuichi for Christmas. During Christmas, Nana even dressed up as Billy to avoid being recognized by classmates, her counsellor, and the vice principal because it was against school policy for students to take on part time jobs when they should be studying for entrance exams.
- DJ 623 (Mutsumi Hojo) - The host of the Examinee #623 radio show. He gives advice on various topics, including good luck charms and studying tips. When Nana and Hitomi run into him on the train to school, he was pleased to meet two of his fans. He asks people to send faxes during his radio show any time they want someone to know something. He is upbeat and quite friendly, with noticeably bright blue hair, and even has the nerve to rub Mr. Handa's head and remark it is like a mushroom. DJ 623 is also a character in the anime Keroro Gunsou (Sgt.Frog) named as "Saburo Mutsumi". Voiced by: Akira Ishida (Japanese), Sebastian Arcelus (English)
|01||First Problem! Nana times Nana is NANA?
"Dai-ichi-mon! Nana kakeru nana wa NANA" (第1問!ナナ×7=ナナ?)
|02||Chaos! All seven of us go to school?
"daikonran! shichinin sorotte gakkou he?" (大混乱!7人そろって学校へ?)
|03||Do seven Nanas make one Nana?
"Shichinin minna de hitori no NANA?" (七人みんなで一人のナナ?)
|04||The birth of the exam hell squadron Nana rangers?
"Tanjou! Juuken sentai NANA RENJAA?" (誕生!受験戦隊ナナレンジャー?)
|05||Decision time! Yuichi's first-choice High School?
|06||Examinee n° 623! Late-night radio commotion?
|07||Midnight snack munchies! A cook-off to help us pass our exams?
|08||Confess your love in english! KO the american tutor?
|09||Sweet temptation! Love, secrets and crib notes?
|10||The dreaded F! Final exams are a must-win battle?
|11||Have your cake and eat it too?
|12||Hot summer study retreat! Heartstopping test of courage and love?
|13||Love & English conversation! A mid-air rendez-vous with Yuichi?
|14||Overseas study program! Chaos in San Francisco?
|15||To each her own entrance exam! Who will catch the future?
|16||Cultural festival heartbreak! A 4-Handkerchief tearjerker?
|17||The day Nana disappeared... and reappeared?
|18||Confession in the snow? Happy christmas from us all!
"" (雪降る告白?ナナとみんなのHappy X'mas!)
|19||New Year's Eve with the whole family! Panic! Mom and Dad return!
|20||Passing grade guaranteed! Charms gone awry?
|21||The missing pencil! There are 8 Nanas?
|22||Showdown! Nana and Yuichi! Interview for early acceptance?
|23||Early acceptance retracted! My love life and my exams are out of control?
|24||The day before the exam!! The last battle, Nana vs Nana?
"" (受験前日!!最後の対決 ナナVSナナ?)
|25||Acceptance announcement! Flowers blossom on the hill of hearts?
|OVA||It's New Year's! 7x7=49 Nanas?
"" (お正月だよ! 7×7=49人のナナ?)
(DVD Volume 7)
In other media
- Sgt. Frog
Sgt. Frog's mangaka, Mine Yoshizaki, created the character concept designs for Seven of Seven. As such, various crossovers exist between the series. The character of Mutsumi Hojo, who appears as "Examinee 623" and the host of his own radio program in 7 of 7, is a major character in Sgt. Frog. Melody Honey, a minor character in Sgt. Frog, appears as Yuurei-chan in episode 12 of Nana.
In addition, episode 89 of Sgt. Frog features a plot that splits Corporal Giroro into seven personalities, most of whom resemble Nana's split personalities. A segment of the episode featuring Mutsumi takes place at the cherry tree seen frequently in Seven of Seven.
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- The DVD-only special takes place after Episode 19: "New Year's Eve with the whole family". The broadcast on Fairchild TV in 2006 aired this episode the chronological order it took place instead of after the series.