The entire timeline of the story spans years, but while she isn't seen for much of the series, she technically plays a large role and becomes somewhat symbolic.
The turnaround (design) shown is her human form. She is about 5' 5".
First and foremost, almost all characters in The Tragic Story of Silhouette presumably HAVE a name, but never reveal it. This is why the series refers to this character as "The First".
To understand this girl in full, it's best to give Act I and II of the first comic a read, but her exact characteristics and personality aren't truly revealed until way later in the series. She is first revealed to be fun-loving, caring, gentle, sweet, and fairly smart, the latter of which is very rare among kids of the facility she lives in. During this time she's shown to be dating a boy with similar traits to her, and they complement each other fairly well. They both don't believe the propaganda fed to them by the adults and\or mandatory classes, nor from the other kids, and don't seem to care what others think of them or do. They would often roll in the grass near the forest together (a place everyone was instructed NOT to go near), stick with each other (rather than the other kids), and share everything with each other.
She would cut her time at this facility short however, as she began to have trouble with her studies. Though her (at the time) boyfriend would have stopped at NOTHING to help her, she didn't want the help, for she didn't want to appear weak. Moreover, she didn't want him to see her so miserable, as this quickly developed into a lack of social life, thus making the other kids think weirdly of her. This eventually drove her over the edge, turning this once charming girl into a husk of who she once was. This would also be the last her boyfriend ever saw of her for many years, something he would come to beat himself up about through most of the series.
Fate and determination make these two meet again, but not as one might imagine. The entire story of her and her beloved is somewhat symbolic, but it also stands as a testament of who she is, for she did NOT mean any harm by her actions. She knew that her love took the small things to heart, and she knew it would eat him up inside to see her struggle, but she didn't know that it would hurt even more to leave him the way she did. She would also never be the same person again, both mentally, and physically, as in their next meeting, her appearance would be drastically different. This speaks to her personality, as she had a good heart, but was mentally weak, arguably even more so than her boyfriend, who was going through some of the same mistreatments at the facility.
The decision wasn't an easy one, and she'll never forget him, just like he can't forget her. He doesn't wish harm on her either, naive as he may be, he loves her still, but grows to realize a part of life is letting go, seeing her one last time before going down in history to fulfil his destiny given from creation.