And here we go, with the character! Added note on Zanpakuto abilities at the end, since its Kidou based I figure you would like some detail on what I was envisioning it to work like. Do tell me if its too much :)
Name: Shizuka Kunakita
Desired Rank: Captain class (9-10)
History: Shizuka had always been a bright, and intellectual woman, even at her early days of the academy. She rose through the ranks easily, her power and her own ability aiding her ascent in the ranks of the 13 squads. Her upbringing in Inazuri, one of the worst districts for a girl on her own. She had no one, no family, no friends, constantly fighting to survive the harsh environment around her, and become better… stronger, so that she didn’t have to be afraid. Every day was a lesson in fear for her, a frightful girl who had no idea where she had ended up in the world, after being a wandering spirit for so long in the world of the living. Though her salvation came the day her spirit power manifested itself, and caught the attention of a passing Shinigami, who helped her get out of that dangerous place, into an area of Rukongai that would be much safer for her. From there, she devoted herself to becoming a Shinigami, a kind, and gentle soul much like the one she idolized for rescuing her from her own fear…. As she practiced, and trained, studied and toiled, she was finally accepted into the academy, to train and learn to become a real Shinigami.
Having shown rather exceptional aptitude to Kidou, and sword play, she was a prime candidate for acceptance into a squad, and her belief in herself, and her devotion to her training was vindicated the day she was officially accepted into the Gotei 13. Her skill and ability only grew under the care and help of her comrades, finally feeling like she belonged someplace, and didn’t have to be afraid, she grew to become a fearless, and bold woman, with a pure heart and gentle mind. One single day had changed all of that, when she and her unit were attacked in the world of the living by a rather powerful hollow… one like they had never seen. Her soul was partially devoured by the hollow, the only thing that had stopped it was a lucky strike from her Zanpakuto, which carries a unique Kidou based set of abilities. In her wounded state, the hollow taint that had damaged her soul took a deep root, and fed from her Reiatsu, twisting its way into the very core of her being, and awakened her hollow power…
Appearance: Shizuka is a slightly tall woman, standing at 5’7, with a moderate yet attractive build. Her form tone, and lithe from years of training and physical activeness, with smaller than average curves. Her hair is long, easily reaching the center of her back, and freely hanging, as pony tails make her feel uncomfortable. Her eyes are a deep emerald green, and her skin is smooth, and lightly tanned, with easily seen scars from various battles dotting her body, mostly hidden by her clothes, save for the few on her shoulders, and arms.
Zanpakutou Name: Kurai shuujin (Dark Prisoner.) Akuryou shihaisha, Kurai shuujin (Evil Spirit lord, Dark prisoner (Bankai name)
Zanpakutou releases and appearances: Kurai shuujin appears in its normal state as a Nodachi, a larger and longer than average Katana, with a blade nearing 4’5” in length, and a hilt that is 10 inches long, bringing the overall length of the blade to 5’3 inches in length, nearly as tall as Shizuka herself.
Shikai release: “Punish the Wicked… Kurai shiijin” In its released form the blade maintains its overall shape to a degree, but the blade itself is thicker from edge to back, and the blade itself resembles a long edge of serrated fangs, perfectly aligned, with a black hilt and a dark purple streaming ribbon of pure reiatsu hanging from the end of the hilt, listing in the wind to give it no more than its appearance to question. The blade itself seems to be shifting… like shadow and fog moving within crystal, giving it the appearance like the long blade is made of the swarming shadows itself.
Bankai Release: “Akuryou shihaisha, Kurai shuujin” The demon lord, or Evil spirit lord, is the name of the bankai release of her Dark prisoner. The blade twists into an instrument of death, much like the weapon of its name, the “Demon Lord” The once long Nodachi becomes a large scythe, with a blade that looks like it is made from pure Onyx stone, a deep, impenetrable black color that gives off a black fog, like ice laying on the pavement on a summers day. The scythe shaft stands at 5 foot 11 inches tall, with a blade that extends forward in the shape of a cruel serrated claw for 2 feet 8 inches. The scythe has hanging from it in 4 places around the shaft on the same level, 4 chains that connect to her right arm, which is covered by a black armored gauntlet from hand to shoulder now. The chains can extend on will, giving her the ability to use the gruesome weapon as a ranged attack, as well as activating her most powerful Kidou based abilities, since the nature of her Zanpakuto is Kidou based. Upon activating her bankai, the shadow itself swarms around her in a torrent that is not unlike a small tornado of raw Reiatsu, bursting away upon completion, leaving her clad in the right gauntlet, with the weapon grasped firmly in hand.
Hollow Name: Same as real name.
Hollow Powers: The only power she can control with certainty with her mask on, aside from the norm of increased speed, power, and agility, is that she has managed to manifest and fire powerful Cero attacks, since the hollow power had spent so long feeding from her Kidou before she became a vizard. Regeneration rate is slightly better, but nothing close to high speed regeneration like many other Vizard. Given the nature of her Bankai, her Cero is colored in a deep black, that seems to glow a dark purple around the outer energy of the main beam, aid is fired from the fingertip, making it a narrow Cero, only about the circumference of a softball, but no less devastating.
Kage no keimusho (Prison of Shadow): By stabbing the weapon into the ground, or any solid surface, Shizuka can form a large circle of shadow anywhere in her field of view, causing the shadow itself to consume her enemy in a prison of pure darkness. Once held, she normally uses it to hold them in place long enough to channel devastating Kidou attacks using the full incantations for increased power. The prison itself does nothing to harm anyone, and only works on those standing on a solid surface. It can be broken out of, as it is a kidou based ability, but only by those that possess some affinity with barrier type Kidou, or those that can shatter it with their own Reiatsu. (Only usable in Shikai and Bankai)
kurai akari (Dark Light): A rather simple ability by most means, A stroke of the blade releasing a dark wave of shadow that contains explosive amounts of power, usually detonating upon impact, can be used in Normal form, Shikai, and Bankai, with the effect growing more powerful per stage of release.
Final ability, Ankoku no arashi (Tempest of Darkness): The final ability of the Dark prisoner, called the Tempest of Darkness. By slamming the end of the shaft of her scythe into the ground, Shizuka causes a large dome of shadow to consume a large area around her, aimed at sealing her and her opponent(s) inside. Within the large dome of shadows, there exists no sense of direction, yet they can see like they are in the light of day, there is only darkness surrounding them both, like a world of infinite blackness. Within, there is no obstruction between enemies, always a clear line of sight, nothing to flee behind unless used in urban areas. Within the dome, her strength and speed are increased twofold, and her kidou is augmented, easily twice as powerful even without the use of incantations, the goddess of her world in all manner of speaking. The major drawback is that if enough time is spent forcing your body and mind to figure out where it is, the shadowy confusion that is placed on her opponents mind will shatter, and they can leave the dome, her tactic to prevent that is usually to remorselessly assault her enemy, giving them no such thinking time. To break in from the outside, you would have to possess amazing power, or an immense knowledge of binding Kidou spells. (Can only use in Bankai, and cannot be wearing her Hollow mask while inside of the dome, or it will immediately shatter)