A well-written start; I really like the idea you have here. You've given a bit of information, but not too much, just enough to keep the reader interested. Good job. :-)

OriginalityComment: Introduction method and structure posses no cliche. Very commendable.

Suggestion: Concept has been used often. Be sure to set it apart.

CharacterComment: Introduction and development of "Sara" are incredibly well done.

Suggestion: Primary physical description (red) is incredibly good. Subsequent descriptions tend to drag, and seem unneccessary.

PlotComment: Introduction introduces plot well, sets tone for the story. Reflective voice is spot on.

Suggestion: N/A. To early to tell, Good so far.

TechnicalComment:

one could qualify her beauty

wearing a cute skirt and a slim dressy short sleeved skirt.

Their appearance became that of the monsters that they hide so well.

They stimulated the the system

Suggestion:

one could quantify her beauty

wearing a cute skirt and a slim, dressy short sleeved shirt.

Their appearance became that of the monsters that they hid so well.

They stimulated the system

OverallThis is a real diamond in the rough, isn't it? Beautiful start, looking forward to reading more.

Keep it up.