The short-tempered, diminutive classmate of Rin Kokonoe and Mimi Usa's in class 4-1 (originally 3-1) at Futatsubashi Elementary School, who has been close friends with both of them since they were in first grade. Originally the stereotypical spoiled rich kid — egotistical, possessed of a superiority complex, and quick to mock, judge, and deride others — her involvement with Mimi and Rin began after the three of them, the "class misfits", grouped together for physical education class, during which the former two of them discovered that the latter's mute, detached state was the result of trauma from her mother's death. Initially, Kuro's "friendship" with Rin was rather warped, as she viewed the latter as little more than her personal plaything, applying things such as makeup and nail polish to her as if she were a living doll (and getting into trouble for it). However, it was during an attempted "dress up" session that Kuro had her arguably greatest impact on her friend's life: her attempt to remove a dress that Aki had made by hand for Rin prompted the latter to emerge from her trance for the first time to protest the action, marking the beginning of her long journey on the road to eventual recovery.

While Kuro's attitude improved somewhat in the ensuing years, her friendship with Rin changed dramatically: the admiration and respect she developed for the strength of character that emerged in her friend eventually gave rise to a lesbian attraction. Though she has made several attempts to make her feelings clear, they are always completely misunderstood and misinterpreted by the object of her affection, and her unrequited love has been the source of much anger, grief, embarrassment, and frustration in her life and remains a sensitive subject for her. In spite of this, she remains fiercely loyal to, protective of, and dedicated to Rin, a courtesy she extends to any individuals she considers her friends.

One quality of hers that has not changed in the intervening years, however, is her obsession with following the latest, expensive fashion trends, a vice which the wealth of the Kagami family, combined with her only child status and a loving yet overworked and absent mother, has allowed her to indulge in to no end. She often wears clothing in the Gothic Lolita style, sometimes combined with nekomimi ears and tail, and has claimed in the past that she purposely chose to attend a public school because of the restrictions on her wardrobe a private one's dress code would have imposed upon her.

Though Kuro frequently serves as Rin "partner in crime" due to their comparable levels of sexual knowledge and mutual disdain for authority figures and adults in general, their opinions differ radically when it comes to Daisuke Aoki. The open contempt she shows for him stems from the erroneous notion that he is a phony, i.e. that any praise he offers or concern for the happiness and well-being of his students he demonstrates is part of either a condescendingly insincere attempt to flatter his pupils into yielding to his authority or a facetious prerequisite of his job as an educator. That she also believes him to be both incompetent and naïve as well as a pervert, lolicon, and rival for Rin's affection have not helped matters any, and she has become determined to never let him live down the fact that he is a virgin once she learns of it. On the other hand, she has come to idolize and develop something of a crush on Sae Shirai, viewing her strict, no-nonsense attitude towards children as evidence of sincerity, and has managed to cultivate a genuine, if unspoken, friendship with her, albeit not without encountering a few bumps along the way.

Recently, Kuro's growing concerns over changes in Rin's pattern of behavior led to a dramatic confrontation between her and Aoki during which she, without betraying any confidences, stated in no uncertain terms her belief that he cannot banish her friend's demons simply because he is incapable of providing her with the romantic love she wants and needs from him. Though heartbroken by Rin's decision in choosing him over her, Kuro has tried putting some of her animosity towards Aoki aside — or at least as much of it as she can stand to — for the sake of her friend, in the hope that he can be her salvation.

Source: Wikipedia