Kuroka

Kuroka is a Nekomata and a member of the Vali Team previously belonging to the Khaos Brigade. She is the older sister of Koneko Toujou, and an SS-Class Stray Devil who was one of the Underworld's most wanted criminals.

Appearance
Kuroka is a young woman with a voluptuous figure, long black hair with split bangs and hazel eyes with cat-like pupils.

Her attire consists of a black kimono, a yellow obi, a set of golden beads, and an ornately detailed headband. The kimono features a red interior and it is open at her shoulders, giving view to her large breasts which rivals Rias and Akeno in terms of size.

In her Nekomata form, which she is mostly in, she grows a pair of black cat ears and two black tails.

Personality
Kuroka seems very playful, easy going, simple minded, and enjoys teasing people. She's also vulgar, using her beauty and sensuousness as a weapon in her arsenal of teasing. Kuroka loves her little sister Koneko dearly, though she seems to have trouble showing it at times, preferring to tease her.

She has expressed an interest in having strong children, having propositioned both Vali and Issei who both have Heavenly Dragons inside of them. It is hinted that the reason as to why she wants to have strong children is because she wants her species to bloom once again, as their species is currently on the brink of extinction.

Adding to her feline personality, Kuroka often ends her sentences with "Nya" (にゃ), mimicking a cat's meow.

History
Kuroka is the older sister of Koneko (then as Shirone) who was born to a rare species among the Nekomata, called the Nekoshou. After losing her parents, she and her sister were later taken in by an unnamed Devil, and she was reincarnated as the Devil's Bishop using two Evil Pieces.

While serving her master, she became extremely talented in Senjutsu and Youjutsu, and her magical power as a Bishop became so great that she surpassed her own master in terms of magical power alone. This later became her undoing when she later became a Stray Devil after she killed her master, with everyone assuming that she was drunk with her own powers, but the real reason was to protect her sister from her master, and became the cause of her sister's near-execution and depression as well as the reason why she refuses to use Senjutsu and Youjutsu. Following the incident, she became one of the Underworld's most wanted criminals, ranking at SS-Class. At some point before the series, she joined the Khaos Brigade.

Birth of the Breast Dragon Emperor
Kuroka appears in Volume 5 during the Young Devil's Gathering alongside Bikou, attempting to take her sister despite Vali's orders and Bikou's warnings. She was then confronted by Issei and Rias, and fought the former after incapacitating Rias and Koneko with her poison mist Youjutsu, knocking down Issei in just two hits. However, the tides turned when Issei poked Rias' breasts to achieve his Balance Breaker. After being warned by Issei who stopped his fist before striking her, Kuroka retreats from the battle with Arthur Pendragon covering her and Bikou's escape.

The Heroic Oppai Dragon
She reappears in Volume 7 alongside her Vali Team teammates in a temporary alliance with the Gremory Team to battle Loki and Fenrir. Prior to the final battle, she asked if Issei is interested in having a sexual relationship with her mainly because she wants his "genes" for strong babies, which she tried with Vali but he denied. During the final battle, she was the one to transfer Vali and Fenrir to a different place in an attempt to capture Fenrir.

In Volume 11, she, Fenrir and Le Fay Pendragon acted as Ophis' bodyguard in the Hyoudou Residence, negating Koneko's mating season. During the attack by Cao Cao and Georg, Kuroka and Le Fay used a magic circle to switch Vali and Fenrir's position, allowing Vali to join the fight. Kuroka, however, was injured while protecting her sister after Cao Cao redirects Vali's attack to Koneko. While recuperating from her injury, she reveals to Issei that her previous master was a power-hungry person who would make even his servants and their family go through crazy power-ups, and intended to use Koneko as an experiment to test the power of a Nekomata, therefore Kuroka was forced to kill her master to protect her sister. She later proposes to teach her sister the Nekomata's Senjutsu and Youjutsu, and is somewhat surprised when Koneko agreed.

In Volume 12, she and the rest of the Vali Team were hiding in the Gremory Palace while waiting for Vali to recuperate from his curse that he received from Samael. She and the rest of the Vali Team later go to the Realm of the Dead and started a fight with the Grim Reapers under Hades.

The Legend of Oppai Dragon and his Lively Companions
She, along with Le Fay Pendragon, later move into the Hyoudou Residence in Volume 14 as semi-permanent residents so that she could teach her sister on how to use her powers better while making a mess out of Issei's house (much to his dismay) with Le Fay apologizing for Kuroka's actions. After seeing Kuroka reading a book regarding Senjutsu to teach her sister, Issei asked if Kuroka wanted to reconcile with Koneko but Kuroka feels that she did something horrible to her sister even if it was to protect her as she was blamed by many Devils and was even nearly executed. Issei reassured her that he would help the two sisters patch up their relationship when the time comes, adding that Koneko's smile was the most important thing to him. Kuroka finally understood the reason why all the girls around Issei were falling for him, claiming that he was more charming than normal handsome men. She was later absent during the attack of Khaos Brigade due to Vali calling her and Le Fay back to assist him with his own battle.

She appears again in Volume 15, where she and Le Fay talk about the Vali Team's battle against Aži Dahāka and later recomends Le Fay as Issei's pact magician.

In Volume 16, she and the rest of the Vali Team participated in the meeting for the formation of D×D and became the house guests of the Hyoudou Residence.

Powers & Abilities
Magic Talent: As a Bishop worth two Bishop pieces, Kuroka possesses great magical abilities and talent.

Senjutsu and Youjutsu Expert: Kuroka is a very skilled Senjutsu and Youjutsu user, being able to create mirage copies of herself to throw her opponents off. She is capable of combining both her techniques to fire concentrated blasts of energy. She can also create a poisonous mist to restrain her opponents. Dragons, however, are immune to it. Stealth: Kuroka uses her Senjutsu to conceal her presence from other Devils by changing her ki flow.
 * Space-Time Manipulation: She is also capable of performing space-time manipulation, though at this point she can only manipulate space.

Trivia

 * Kuroka's body measurements are B98-W57-H86 cm. (B39-W22-H34 in.) and her height is 161 cm. (5 feet 3 inches), as stated in an issue of Dragon Magazine. Her breast size is recorded as the third largest in the series, behind Rias Gremory and Akeno Himejima.
 * Kuroka's name means "Black Song", in reference to her hair and tail color.
 * In one of the illustrations from Volume 7 of the light novels, Kuroka's ears were colored white instead of the original black. An error that will be later corrected as shown in Volume 11.
 * Kuroka makes Le Fay do her laundry as she's lazy to do housework in the Hyoudou Residence.