- A-ko (A子) (Eiko Magami (摩神 英子 Magami Eiko ))
- A-ko, a red-haired girl who seems to be near invulnerable with superhuman speed and strength, is the heroine of the series and lives in Graviton City, Japan. A-ko is usually very friendly, cheerful, and polite and always tries to lead a normal life despite abilities. However, she does have a fiery temper and is very dangerous when angered. She has a large appetite and a tendency to oversleep on school days. Her constant friend is C-ko Kotobuki, whom she has known since kindergarten. Although A-ko can sometimes be frustrated with her, she truly loves C-ko. Both are transfer students to Graviton High, but wear their former school's sailor-style uniform for most of the film.
- B-ko (B子) (Biko Daitokuji (大徳寺 美子 Daitokuji Biko ))
- B-ko Daitokuji is well-known in Graviton High as the daughter of a local industrial tycoon. As a scholastic genius, she is seen living a luxurious lifestyle including limo rides to school and carrying haughty airs in her demeanor. At school, a small group of classmates act as her loyal subordinates.
- Although seemingly very calm and poised in public, and always deferring to her teachers' authority, B-ko has a tremendous temper which flares whenever she doesn't get what she wants. Her desire to steal C-ko's affection away from A-ko develops from regular obsession to all-consuming, devoting all her resources, her subordinates, and her mechanical genius to her goal.
- C-ko (Shiiko Kotobuki (寿 詩子 Kotobuki Shiiko ))
- C-ko Kotobuki is A-ko's best friend and has depended on her since they met in kindergarten. Though the same age as the other two girls, C-ko can be considered quite childlike. She is described as cute and innocent, tends to be hyperactive, and, in the Japanese version, frequently refers to herself in the third person, a trait associated with being childish. C-ko can often be sensitive and immature, and because of this, she has a tendency to cry.
- In the first installment of the series, C-ko is revealed to be the Fourth Princess of the Fifth Queen of the Lepton Kingdom of Alpha Cygni, an all-female race of extraterrestrial aliens. She crash-landed on Earth when she was an infant, and the Lepton Kingdom has been searching fervently for her ever since. However, C-ko is fairly uninterested in her unearthly ancestry and wants nothing more than to remain on Earth with A-ko.
- C-ko enjoys cooking, but the food that she prepares is largely inedible and often contains ingredients not meant for human consumption.
- Captain Napolipolita
- Napolipolita is a captain in the Alpha Cygnan space navy, who has spent the last sixteen years searching the universe for C-ko. Although she first appears to be a man, it is later revealed that the Alpha Cygnans are an all-female race, some of which resemble males. Although Napolipolita cuts a fine figure, always impeccably dressed with a dramatically-swirling cloak and wraparound sunglasses, her facade quickly shatters when danger arises. During the long sojourn in space, she has become completely addicted to alcohol and unravels when she is unable to get a drink.(Capt Napolipolita is an obvious parody of Capt Harlock)
- D (Operative DC138621-S113)
- As a spy for the Lepton Kingdom, D has been stationed on earth for a long while, searching for signs of their missing princess. Her long exile comes to fruition when she encounters A-ko and C-ko racing to school one morning. She continues to stalk the pair, despite suffering massive (but accidental) bodily harm whenever they meet.
- Like the Captain, D is in fact a woman, but appears very masculine to Earthling eyes. This confusion is cleared up at the end of the first movie, when she dons a very scant uniform to battle A-ko.(Operative D is a parody of the Character D from Vampire Hunter D)
- Miss Ayumi (亜弓先生 Ayumi-sensei )
- Miss Ayumi is a teacher at Graviton High School who has A-ko, B-ko, and C-ko in her class at the same time. This means that she has the task of trying to get C-ko to learn while preventing A-ko and B-ko from murdering each other.
- Miss Ayumi is modeled after the lead character of the eponymous TV series Creamy Mami, one of several magical girl TV shows that came out during the 80s.
- Mari, Ine, Asa, Ume
- These four girls are B-ko's only friends, although "employees" might be a better term. They spend most of their time doing whatever B-ko orders them to. This can range from reconnaissance work, to piloting B-ko's enormous war machines, to helping her stage commando raids against anyone who dares to cross her. They are apparently not paid well and gripe among themselves that they can only afford to eat ramen noodles most of the time.
Ume is chubby and wears spectacles.
- Ume voiced by Megumi Hayashibara (Japanese)
Ine is skinny and buck-toothed.
- Ine voiced by Yoshiko Takamori (Japanese)
Asa is fairly normal-looking.
- Asa voiced by Yoko Ogai (Japanese)
Mari stands at least eight feet tall with tanned skin and an enormous musculature. She is an obvious parody of Kenshiro from the anime/manga series Fist of the North Star. She looks quite a bit like him, uses a similar fighting style, constantly tatters her clothing when flexing and has many of his mannerisms; however, her speaking voice is a normal female one.
- Mari voiced by Daisuke Gohri (Japanese)