Akemi Sakai

Origins
Akemi Sakai, was girl who suffered through some hardships throughout her life. This is mainly caused by her abusive father whom was a dangerous criminal. He would physically assult both Akemi and her mother constantly. Due to her father's actions, it lead to Akemi's mother death which resulted in his arrest. With her mother and father gone, she was taking in by two FBI Agents Raye Penber and Naomi Misora. They were the two investigators that helped with her father's case and inevitable arrest.

When KIRA appeared one of the very first people to be killed during his purge was Akemi's father. This lead her to take great interest in him and eventually become a supporter. However, by some twist of fate a Death Note appeared before Akemi. After reading the rules and reviewing over all the killings she was able to deduce that KIRA was notebook owner. With that realization, she would use her new power to aid in KIRA's mission.

While the police weren't aware of the existence of this new KIRA, Light referred to this one as X-KIRA due to her work being hidden within the shadows. Eventually the two were able to meet and joined forces in order to kill L and to make the world a better place.

Personality
Akemi is an exceptionally intelligent and resourceful woman, but not above using questionable and even outright amoral methods to achieve her planned goals.

She possesses a profound respect towards KIRA and his mission in riding the world of evil. The reason for this was because he managed to kill Akemi’s father who was a monster to her and her mother.

Despite her intense hatred towards criminals, she has shown to be rather level headed and cunning when it comes to using the Death Note. Akemi was able to utilize it’s power just as effectively as Light by studying his actions through the media.

Abilities

 * Genius-Level Intelligence: Akemi's intellect seemingly put her on par with Light Yagami and L Lawliett. She possesses the ability to quickly process multiple information streams like threat assessments and rapidly respond to changing tactical situations. Akemi has incredible analytical and deduction abilities that rival that of L, with Light Yagami saying he was impressed with her investigate skills. Her mind also processes information quickly, giving her an accelerated learning aptitude. She possesses an eidetic memory (she never forgets anything and has perfect instant recall), she can read at superhuman speeds, and can intuitively understand what's going to happen and how to deal with it.
 * Master Strategist: Akemi can instantly create strategies and plans several steps ahead of her enemies and allies alike, with Light Yagami stating that she could see five steps ahead. She is able to elaborate complex strategies and apply them in not just battle, but any other activity as well. She was also able to outsmart L since no one suspected in the existence of a second KIRA and infiltrate the Task Force leaking information to Light with none the wiser.
 * Master Infiltrator: Akemi is highly skilled in espionage and infiltration. She's able to successfully work under cover for months, steadily leaking progress of L and the Task Force's actions to Light, and doing it so skillfully that none of them ever suspected her or caught her in the act.
 * Polymath: She has studied Biology, Technology, Mathematics, Physics, Mythology, Geography and History. Akemi gained degrees in Criminal Science, Forensic Sciences, Computer Sciences, Chemistry, and Engineering by the time she was 21.
 * Multilingualism: Akemi is fluent in Japanese, English, French, German, Chinese, Russian, and various other languages.
 * Master Martial Artist: Akemi is well-versed in martial arts and hand-to-hand combat, due to Namoi Misora and Raye Penber teaching her when she was very young.
 * Skilled Marksman: Akemi is a proficient marksman and can throw most projectile weaponry with great aim. She is also competent in the use of firearms, though she prefers not to use them.

Death Note

 * The Human whose name is written in this note shall die. This note will not take effect unless the writer has the subject's face in mind when writing his/her name. This is to prevent people who share the same name from being affected.
 * The Death Note will not ever affect a person whose name has been misspelled four times.
 * If a Death Note owner accidentally misspells a person's name four times, that person will be free from being killed by the Death Note. However, if the Death Note owner intentionally misspells the name four times, the owner will die.
 * When the same name is written in two or more Death Notes within 0.06 seconds, the entry is regarded as simultaneous; the Death Notes will not take effect and the individual will not die.
 * When the same name is written in two or more Death Notes, the note which was used first will take effect, regardless of the time of death.
 * The Death Note will not take effect if the victim's name is written on several different pages. However, the front and back of a page is considered to be one page. For example, the Death Note will take effect if the victim's last name is written on the front page and first name on the back.If the cause of death is written within 40 seconds of the subject's name, it will happen.
 * If the cause of death isn't specified, the victim dies of a heart attack in 40 seconds. However, the rule can be delayed for twenty-three days, meaning you can write down "dies by heart attack in [xx] days."
 * After writing the cause of death, the details of the death should be entered within the next 6 minutes and 40 seconds.
 * If the time of death is specified within 40 seconds after writing the cause of death as a heart attack, the time of death can be manipulated and can go into effect within 40 seconds after writing the name.
 * The conditions of death will not be realized unless they are physically possible for that human or could be reasonably assumed to be carried out by that human. Although it is possible to control a person's actions, if an impossible situation is written down the person will simply die of a heart attack.
 * You may write the cause and/or death prior to filling in the name of the individual. Be sure to insert the name in front of the cause of death. You have about 19 days (according to the human calendar) to fill in a name.
 * After an individual's name, time of death, and conditions of death are entered in the notebook, the time and conditions of death may be altered as many times as desired as long as they are changed within six minutes and 40 seconds from the time they are filled in. But, of course, this is only possible before the victim dies.
 * If you write "dies of accident" for the cause of death, the victim will die from a natural accident six minutes and 40 seconds after the time of entry. "Accident" is a condition of death, so six minutes and 40 seconds are provided to write down additional details. The conditions do not take effect until this time has passed.