Sialim Eltnam Re-Atlasia is Rani’s teacher. She was also the last alchemist, and the one who created Rani.
After sending Rani off to the Moon, Sialim died of sickness.
As an Atlas Institute alchemist she was completely focused on her research and only her research, but as her final work before death, she worked not as an alchemist, but as a human being, and created Rani.
The reason that Sialim orders Rani to go to the Moon is to verify if humans can abandon their bodies and continue to live in the cyber world.
Magus pursue the goal of “evolving to be higher level beings” but Atlas Institute alchemists do not.
The Atlas Institute’s primary goal is to avoid a future where mankind is destroyed.
In short, this means that Sialim is not bothered if all of the human race must change form or regress as long as they secure their continued existence. Sialim surely just wants to carry out the Atlas Institute’s mission.
…Also to that end, Sialim coldly ordered Rani, “If Moon Cell doesn’t have what it takes, and is a monster that cannot be controlled, incinerate it completely, including yourself.”
In EXTRA you might have noticed that Rani says “teacher”1 at one point. Sorry, just forget about that. Also, there might have been something about Sialim having a twin older sister who died at birth.
- ^ Teacher (師父) here is masculine, implying Rani referred to her as a “he.”