This is Emiko's back story up until her placement with Henna and Neji.
Hatake Kakashi and Nara Keiko married at the age of sixteen, a year after the Kyuubi's attack and Naruto's birth. Keiko was six months pregnant with Emiko when they married, and they were both exceptionally happy.
Until Keiko went into labor unexpectedly early. She was with her sister-in-law, Yoshino, when it happened, and she sent Shikaku to fetch a medic and Kakashi. They were barely able to save Emiko's life, but Keiko died as soon as Kakashi swore to take care of their daughter. Kakashi was heartbroken, and fiercely protective of Emiko after almost losing her. He resigned from ANBU, and took Emiko back to his family home.
He knew nothing of caring for a newborn, and without Keiko's guidance it didn't take long before Kakashi begged the Hokage to assign him a genin to assist him in caring for Emiko. Hiruzen assigned Iruka, with the condition that Kakashi train the boy. Kakashi agreed, and Iruka came into their lives. For Emiko's entire childhood, Iruka was her caregiver while Kakashi was away on missions. The council was very angry that Kakashi had chosen to retire from ANBU, and tried to force him to put Emiko up for adoption, but Sandaime intervened.
Emiko began to show signs of chakra manipulation at the age of four, and Kakashi decided to put her into the academy. Iruka put his foot down and told Kakashi he thought Emiko deserved a real childhood, so Shikaku offered to train his Niece in the Nara clan's secret Shadow jutsu's as a compromise, until she was five and entered the academy.
She was in Iruka's advanced pre-genin class and graduated at the age of six, and was placed on a Genin team under Anko. When she turned seven, Anko entered her team in that year's chuunin exam, which was held in Sunagakure. She didn't tell Kakashi she had entered them, and Kakashi didn't find out until she had taken them and left for Suna.
The Shinobi Council, mad that Kakashi had chosen to be an active parent instead of staying in ANBU and fearful of Emiko's potential, rigged the exam and paid a team of Genin from Kumo to her. Emiko and her team made it to the finals, and were pitted against the genin team from Kumo. The rules of the exam had been very clear; they were to attack like they would in any give situation, but not actually kill. When it became obvious to Emiko's team mates that the older Kumo Genin were trying to kill Emiko, they intervened. It cost them their lives, and they were slaughtered in front of Emiko. In a fit of rage and desperation, Emiko killed the two that had killed her team mates, and was preparing to kill the third member, when Anko, Sandaime, and Asuma, (who was present with the daimyo) stopped her and dragged her from the ring. Sandaime promoted her to Chunin, but Emiko was devastated.
She didn't speak to anyone but her summons (a pack of four dogs, descended from Pakkun, Bull, and Akino.) for over a year. When she was nine, her pack finally had enough of her self-imposed seclusion and forcibly dragged her to Iruka's classroom one day after classes were over for the day. They held her down, and forced her to talk to Iruka. He comforted the girl he'd come to love as his own, and he took her back home where she finally spoke to Kakashi as well.
That night, Kakashi asked Iruka to move in with them, and they began becoming serious even though they'd been sleeping together for a while. Emiko was happy for them, and started to call Iruka Chichiue, and referring to them as her fathers.
She was still loathe to trust people she didn't know, and she absolutely despised traitors. So when Sasuke left, it hit her personally. After Naruto returned from his training with Jiraiya, she went on a mission with team Kakashi, and they stumbled across Sasuke who was injured from his fight with Orochimaru. After Naruto had tried to talk him into coming home, Emiko became outraged at how much Sasuke had changed, and she ignored Kakashi's order to stand back and she attacked Sasuke.
They fought for close to an hour, and Emiko finally managed to come out on top, and pinned Sasuke down. She was preparing to kill him, via Chidori to the heart, when Naruto tackled her and stopped her. Sasuke escaped, and left Emiko seriously injured. Iruka took a leave of absence from the academy to take care of Emiko. About a week after her attempt to kill Sasuke, Tsunade came to check on her and informed her that she was going to be placed on a three man cell with Mizuki Henna and Hyuga Neji.
Emiko was wary, as she had never met Henna, and she had had a crush on Neji since she was 11. It took her a long time to warm up to her new team, but she did. She had no idea how close she would end up to either, or that Henna would become the sister she never had and Neji would someday become her husband.
This is Emiko's physical description
Emiko is 5'4 at the age of fourteen, and grows several inches before her 18 birthday, leaving her at 5'7 when she is fully grown. She weighs a steady 130-140 from the age of 14 and up, most of which is muscle. She's lean and shapely, about a 32D bust, and is toned everywhere else. Her hair is silver like her fathers, and falls down to the tops of her hips. She mostly wears her Hitai-ate like a head band to keep her hair out of her face during regular day to day activities. When she is thinking, fighting, or feeling off, she pulls it up into a bun which she pins in place with senbon or braids it so it hands down over her shoulder. She wields a Tessen that contains secret compartments in each slot of the fan, and shoots senbon when she forces her chakra through them, and she also carries a Katana (or two) strapped to her back. She is a water type, but can also perform several justu's from other elements, including her father's Chidori (which she can't wield unless she is with someone who can immobilize her opponent.) She wears a normal flak vest unzipped to her navel, and a black skirt with a slit on her right side from the waist band to the hem to expose her thigh and weapons holster. She wears a one piece mesh body suit, which is short sleeved and stops about three inches above her knee. She wears plated and fingerless gloves, and one missions she wears a forearm guard on her right forearm. She sometimes wears an ANBU issue black tank with mask attachment. She wraps her feet from right under her toes and all the way up to mid-shin, and wears black standard issue sandals.
She carries her mother's Hitai-ate in her flak vest wherever she goes. She works active missions, but helps Iruka with his pre-genin and in the mission's room whenever she can. She also trained with Sakura in medical ninjutsu, for the sole purpose of being a field medic. She varies between a standard issue uniform and her favored outfit.