Kuroi Nakase is Ryouko’s mother. She is somewhat over a century old.
Kuroi Nakase tends toward the quiet and reserved, but, as an administrator inside the Prometheus Research Institute, is rumored to be unforgiving as a boss, at least towards incompetence. When Kuroi Nakase is explaining something, she has a tendency to lapse into long periods of overly-detailed textbook-like verbiage, an aftereffect of her demand for precision in her work.
She seems to be a loving parent, but disapproves strongly of Ryouko making a contract, believing she cannot handle herself, and has a dislike of the MSY and military. Her marriage with Shizuki Kuma is on the brink of collapse; they nearly divorced before deciding to give it another try after receiving a child license, and Kuroi Abe says they're "at the point where they both find the silliest reasons to get angry at each other". However, the couple hid it successfully from their teenage daughter, who suspected nothing. (In the end, they divorced soon after Ryouko contracted, and was forced to tell Ryouko since she would not be staying at her old room.)
In childhood, Kuroi Nakase had been bright, childish, and bubbly, until her experience with her friend Kavita.
Kuroi Nakase is a former magical girl, something which must be extremely rare. Her experience with her contract was not particularly positive, since she was unfortunate enough to have the team member she wished to save lose her body in front of her, and later, blame her for the incident. Her relationship with her teammates were also strained; though they reassured her, claiming it was not her fault, they appeared not to take her seriously - such as ignoring her claims about her sister suspecting and doing something - and Nakase believes they thought of her as useless. Shortly after initially contracting, her contract was canceled by her sister’s wish after her body was destroyed by a horde of demons.
These experiences fed strongly into her later beliefs and actions, particularly on her work.
As a biologist with a neuroscience and nanotechnology background, Kuroi Nakase contributed significantly to the development of the "blank slate" clones the MSY currently uses to revive magical girls who have lost a significant portion of their body in combat. Now partially retired, she divides her time between attending to family during the day and research activities during the night, including the regular decanting of revived body loss cases.
It was at the Prometheus Research Institute that she met Shizuki Kuma, a while after starting the secret blank slate project.
Her features are softer than her daughter’s, lacking the aristocratic cast to the face characteristic of the Shizuki Matriarchy. It is practically a tautology to say she looks younger than her age, but she looks even younger than her physical age, and is somewhat short of stature and flat chested (though not as much as her daughter). She lacks her daughter’s perpetual serious look, but will easily gain something similar if the situation calls for it. She typically wears her hair down, like her daughter, but in the workplace the hair will be found folded back into a working ponytail. Some may speculate that her hair is blue. Ryouko notes that Kuroi Nana's "gentle and sharply precise" voice reminds her of her mother, except Nana's voice is lower.
During her short period of time as a Magical Girl, Kuroi Nakase had a costume similar in appearance to her daughter's, except her theme color was blue.