She is an amnesiac middle schooler with long, black hair, and a noticeable ahoge. She wakes up naked inside a large suitcase at the start of the story, having no recollection of her previous life, other than her name.
Other aspects of her previous life eventually are revealed. She is a magical girl, which she discovered after instinctively transforming during a battle. She lives with her two friends, Kaoru and Umika, while their parents are working overseas. Kaoru and Umika are also fellow magical girls, and she fights alongside them and four other girls, collectively known as the Pleiades Saints. She also possesses spectacular cooking skills, being able to create a wide array of delicious dishes and desserts, for which she is often complimented.
It is eventually revealed that she is actually the 13th clone of the original Kazumi (whose real name was Michiru Kazusa) after the original Kazumi turned into a witch and died.
At the end of the series, she adopts the surname Subaru (昴), which means "Pleaides" in Japanese.
Kazumi is rather hotheaded. Her mood is very unstable, and can swing between extremes in a couple of seconds. Still, she is cheerful most of the time. Her reactions are very spontaneous: while rediscovering her old life, she is often seen with a very surprised expression. She is kind of a ditz, especially (but understandably so) in situations she is only now rediscovering; for example, forgetting her skirt while transforming. Nonetheless, she is more than capable of rising up to the situation when it is required.
While getting reacquainted with her old life, she realizes she can't, or doesn't want to be, the "old" Kazumi. Instead, she decides to become a "new" Kazumi, starting with a new, and very sloppy, short haircut. However, she keeps her ahoge, claiming (and apparently, rightfully so) that it is a witch sensor.
While she is only getting to know her friends again, she cares deeply for them. She goes to great lengths to protect them, to the point that she lost a battle with a witch out of fear that her attack might hurt Kaoru, which happened in a previous battle.
Besides her cooking skills, she is also quite the glutton. Even after waking up naked in a briefcase after being kidnapped, her main concern is her empty stomach. Her tastes are quite open, eating most things happily. When hungry, she can be messy while eating. She also claims to be able to identify bad people from how they eat. According to to an advice she once received (possibly from Umika), a bad guy never finishes anything: therefore, a bad guy will never finish his food. She is particularly fond of Umika's cooking.
Her earrings are very dear to her. They were a gift, and touching them can trigger her rage.
Prior to the events of the story, she contracted to become a magical girl, but never told anyone her wish. One day, she woke up naked, inside a briefcase, with no memory other than her name. She had been kidnapped and locked in there by an unknown party. While being carried by Yuuri, the briefcase she was locked in was accidentally switched with another man's briefcase, which was carrying a bomb. When she woke up in the would-be-bomber's house she had a fit of anger, but ultimately calmed down when she found the man didn't kidnap her. After she ate a meal, the kidnapper called-the-would-be the bomber, whose name is Souichirou Tachibana, offering to exchange the bomb for Kazumi. Kazumi agreed to go along with it in order to find any clues about her past. At the mall, the police appears to arrest the bomber, but Kazumi jumps in his defense. She recollects a piece of advice once given to her and claims that someone who cleans his plate can't be a bad guy. Neither party backs down, and when explosion is imminent, Kazumi concentrates her mind on the bomb, attempting to make it stop somehow. Meanwhile, an unknown girl kicks the bomb to the ceiling, where it explodes harmlessly: it was a fake bomb, but it is implied it might have turned into a fake bomb by Kazumi's action.
The unknown girl, and a friend of hers, identify themselves as being Kaoru and Umika, friends and roommates of Kazumi. They take her back to their house, where Kazumi quickly find her room and falls asleep. The other girls go out, and leave Kazumi a card warning her that the police detective from before will visit. She takes the time until her arrival to reacquaint herself with cooking, preparing a Strogonoff. Upon the detective's arrival, she offers her a dish. Kazumi then accuses the detective of setting up the entire incident with the bomb, and then coming to her house to kill Kazumi. This prompts the detective to break her plate in a fit of rage, therefore proving, according to Kazumi's rules, that she was a bad person. Infuriated, the detective attacks her, and transforms into a hideous praying mantis-like figure.
In the heat of the moment, Kazumi, much to her own surprise, reacts instinctively and dodges her attacks. She is eventually caught, but when the monster attempts to rip off her earrings, Kazumi suddenly has a series of flashbacks and she then kicks the monster away and transforms into a magical girl (again, to her own surprise). She then strikes back, finishing the fight with a powerful beam attack just as Umika and Kaoru - who had heard the battle over the phone - arrive.
Powers, Weapons & Abilities
Her weapon of choice is a large cross-shaped staff. She can use the cross as a melee weapon at close range, but it's most effectively used to fire magic beams from a distance. Her attacks have a large range, enough to hit the target with pinpoint accuracy even when fired from outside a witch's barrier. Her final attack is Limiti Esterni (English: Outer Limit), a very powerful beam, larger than the cross' width.
Therefore, she's best employed as a sharpshooter in a team: maintaining some distance from the target, and firing away when the opportunity arises while the other girls weaken and distract the target. To take advantage of this, the other six Saints can cast a joint binding spell, Episodio Incrocio (English: Crossover Episode), powerful enough to hold down a witch, making the target a sitting duck for Kazumi's blasts.
Her ahoge seems to have a mysterious ability to track down pseudo-witches, apparently at a farther distance than a Soul Gem could. However, it has no reaction to common witches.
Additionally, in chapter 1, she was able to transform a time bomb into a dud by concentrating. The same kind of power is seen when she turns a witch into a pseudo-magical girl in chapter 6. It is unknown what kind of power this derives from. In Chapter 8, Jubey says her magic is "sacrilege" but then he quickly corrects himself and says it's "destruction". In Japanese, both are the word "hakai", written in different characters.
Kazumi can also use her staff as a melee weapon. It can extend to great length and change into other weapons, such as a scythe and a sword.
As she is a product of the other six Saints' magic, Kazumi has access to all of their abilities, including Umika's barrier, Kaoru's iron defense, Mirai's sword and Saki's thunderbolts and teleportation. Her bell earring rings when using these abilities.
She can also absorb other materials to regenerate her injuries. This ability has only been used on the remains of her fellow clones, and may be limited to them.
- Like Madoka, both are friendly, gentle and they want to be helpful to other people. And they were both initially average magical girls who died and became "special" as a result of their friends' actions.
- Her outfit, sporting dark, suggestive clothes, a magical cross, and a large witch hat, gives her a "cute witch" look. Given that the same name is used for the creatures they are fighting, this gave birth to a number of theories.
- She even has a black cat named Toto.
- The symbol on her earrings resembles her ahoge and her witch's hat, and is in two places on her Soul Gem.
- Apart from functioning as a pseudo-witch detector, her ahoge also seems to respond to emotions: upon reuniting with Kaoru and Umika at the end of chapter 3, it's shaped like a heart.
- The artwork updates in volume 1 of Kazumi Magica reveal that Kazumi's earring-bell is her Soul Gem. This makes her the first magical girl we've seen who doesn't wear her Soul Gem as a ring when she's not transformed.
- According to a Q&A with the author in Volume 2, her cat's name is Toto. This is later revealed in-story in Chapter 12.
- Kazumi's magical incantation in Japanese is, "Chichinpurin", which is a pun on “Chichinpui", a stock magical incantation in Japanese. "Chichinpurin" has been translated throughout the series as “Bibbity Bobbity Boo”. In keeping with the food puns in the chapter titles, “purin” means “pudding”.