Transformative Weapons

Transformation Weapons are living artificial beings that have what is known as the Transformation ability, which allows them to form and reshape almost any part of their body into a weapon by using the nano-machines in their bodies. The purpose of their creation is to be ordered to kill, so they are raised to be skilled fighters and cold hearted killers. So far there are three who are known as Transformation Weapons and they are a females with the bodies of a child, although they can also reshape there bodies to look more adult like. They're also able to use there ability change there own clothing.

The Organization
The Organization is a secret facility that create these artificial beings, one of the scientists part of the Organization was Dr. Tearju Lunatique who created the first Transformation Weapon and did it with her own DNA thus giving birth to Eve. Tearju planned on giving her happy childhood but the organization had other plans, to raise her as a cold blooded killer by chasing Tearju away and create more to sell those with bad intentions. However the Organization was destroyed by Black and Eve was set free.

Golden darkness
After the Organization fell, Eve moved on to be a cold and emotionless assassin known as Golden Darkness. She  secludes her self from any emotional contact, until she was hired by Lacospo to kill Rito Yuuki but was convinced by Lala otherwise, so instead she chose to asse ss him claiming that she will kill him one day by staying on Earth, by doing so overtime she finaly opens up to humanity and has shown a kinder side to her and becomes friends with others and starts having love/hate feelings for Rito, she also becomes closer again with Tearju. She is renamed as Yami.

2nd Gen-Transformation Weapon
Some time after the fall of the Organization in the midst of all the rubble, Mea Kurosaki  awoke from suspended animation and the first thing she ever saw  nothing but destruction everywhere. While wandering around aimlessly through the place lost and confused she meets Nemesis, after their encounter Mea greatly respects Nemesis as her master who raised and teaches her about the life of living weapon and about how Yami is fact her older sister. Mea does not know life outside being a weapon to kill, she is quite sadistic, childish and low educated about certain things like sex ed, she came to Earth to bring Yami back to being a cold hearted killer again but cannot understand exactly why she stayed on Earth and be friends with Humans. Mea tries to understand her sister's feelings become close friends with Nana, as time goes by Mea see's the world in a different light and slowly opens up to humanity.

Project Nemesis
Unlike the previous two, Nemesis is said to have been created by a completely different faction that was organized by the organization that created Yami and Mea. It is stated by Tearju that this project was a failure. Nemesis is a survivor of the project. What caused it's downfall is unknown.

Nemesis
Somehow being the only survivor of this project, Nemesis for some reason headed to the original organization (which was destroyed at the time) met Mea who she took in and taught her about fighting using her abilities and the meaning of there existence, which Nemesis proclaims that it's to kill and having no emotions holding soft emotions holding them back.

Trivia

 * A protagonist from an American TV series Generator rex, has powers similer to the transfomation ability (creating huge machines and/or weapons from a body part of his) because of the nano-machines in his body known as "nanites".