Anti Heroine: On the one hand, she's a lonely young woman desperately searching for her past and fleeing a mysterious organization that apparently wants her dead. On the other hand, she is extremely good at killing people and makes her living doing just that.
Dark Messiah: What Kirika-chan becomes when she attains the legendary mantle of "The True Noir."
Emotionless Girl: Subverted. She isn't truly emotionless, just simply having a hard time expressing her emotions until near the end, when her "real" personality takes over. She has no hesitation in killing large numbers of people; that lack of feeling distresses her.
Enfant Terrible: Raised by the Soldats to be a Noir candidate. Her first assignment was to kill the Boquets when she was age six, complete with overall straps askew.
Kung-Fu Jesus: She is basically viewed as a savior by the superstitious followers of Soldats: An Invincible Warrior destined to destroy evil and injustice in the world.
Laser-Guided Amnesia: She has no memory of her first fourteen years and only knows her name because of a student ID card, which could very well be fake.
Nice Shoes: Her rather distinctive pink shoes have received a degree of Memetic Mutation among fans. They're also nearly identical to the ones she wore as a young child, when she killed Mireille's family, and since the reveal is shot from her feet up it's the first indication of who the shooter was.
Oblivious to Love: Seemingly towards Chloe. It might just have been because she was in "True Noir" state but the fact that Chloe kisses her on the lips while they were both completely naked and gets no reaction whatsoever points to this.
Tyke Bomb: Was about five when she killed Mireille's family.
Unscrupulous Heroine : She's more concerned with the ethics of killing than Mireille and is mostly concerned with solving the mystery of herself. That doesn't stop her from going into business with Mireille and being very good at it.
Waif-Fu: Not as bad as some examples, but she does pull off some pretty impressive stunts.
Anti Heroine: Although she's an amiable person who has no problem having a friendly chat with a shopkeeper, she is a contract killer and has no moral qualms about it.
Anti-Heroes Gone Fishing: The first few minutes of the show are her going back to her apartment on a bright yellow scooter with a bag of groceries. Then she checks her e-mail to see if she has any hit job offers. She also has a tendency to window-shop.
Badass Normal: Compared to the other candidates for the title of Noir, who have probably been trained since the time they could walk.
Blondes Are Evil: For a given definition of "evil" but she probably would be considered such by most normal people due to her occupation. Given the Black and Gray Morality of the show in the end most agree she ends up more on the Gray side.
Can't Catch Up: Compared to the impossibly skilled Kirika and Chloe, even though by normal standards she's still a badass and not someone you cross.
Combat Stilettos: Not as unrealistic as some examples, but her boots still have decent heels on them. Deconstructed too, on at least one occasion she nearly fell from a house roof to her death since her boots lack grip.
Cool Shades: Tragically, she only wears them in one episode.
Dark Action Girl: She's a very successful assassin. "Successful" meaning that she survives all of her jobs.
Defrosting Ice Queen: She's twenty-ish at the start of the show, but about fifty-five in terms of cynicism.
Love Redeems: Towards Kirika, whether you interpret it as platonic or romantic.
Limited Wardrobe: She wears more action and climate-oriented outfits in some episodes, but the majority of her time is spent in the red shirt and black skirt. She is also quite fond of wearing a lavender colored jacket.
Younger than She Looks: According to the series timeline Mireille is at most 20 during the show, while most people guess that she's a good deal older. Part of this is due to Vague Age, since we're not entirely sure how old she actually is. There's also the fact that she's implied to have been living on her own — and working as an assassin — for quite some time now, which borders on the horrifying if she's only 20 now.
Enfante Terrible: The flashback to Kirika's assassination of the Bouquets shows five-year-old Chloe looking on and smiling eagerly as the deed is done.
Even Evil Has Standards: She works with Shao-Li only because she has to, and it's clear that she doesn't particularly like doing so and offs her as soon as she sees an indication that she's turning.
Chloe: Poisonous insect.
Evil Redhead: Her hair changes based on the lighting, sometimes it's purple, more often a deep, dark shade of red. Either way, it looks pretty sinister.
Good Eyes, Evil Eyes: Her eyes are noticeably more narrow than Mireille and Kirika's except when Kirika is in "true Noir" mode which highlight her being on the darker side of the Grey and Grey Morality. They also make determining her exact ethnicity difficult, and the show never clarifies either way.
Defector from Decadence: The Bouquets refused to hand young Mireille to Les Soldats. Shortly afterwards, they were killed.
Face Death with Dignity: She didn't show any fear or hatred towards little Kirika when she came to kill her, just softly asked her to take care of Mireille.
Lineage Comes from the Father: Played with. While Laurent was obviously a huge influence on Mireille and the direction her life took, Odette probably had the largest impact, what with what she said to Kirika before she was killed.
Mama Bear: As soon as she saw Laurent get shot, her first instinct was to reach for Mireille's brother, who was reading next to her chair. She was too late, and the poor boy was killed. Then there's her request to Kirika, where she calmly asks her soon-to-be killer to protect her daughter. (And boy, would Kirika later follow these words.).