Descendants : Firmament

Sixteen-years-old Chelly Lynch was the Elsworth High's prodigy. Renowed as "Science Queen" schoolwide, Chelly led pretty much a normal life : clubs, friends, hang-outs, despite her straight-A grades. Her life was outright cakewalk, and it's the least of her worries.

But her fate told her a different story...

It almost like she was put in a fantasy book. Inexplicable events took her to another world. Einingheim, a place where various worlds collide, and blessed with potent energy source, Mana. She found herself in the city fortress Firmament, the last frontier of humanity struggle against invasive race Akashian, trying to snatch Midgard out of the hands of humans.

Descendants: Firmament revolves on the epic strife of Chelly Lynch, along with elite force of Firmament which includes unit captain, also her classmate Aiden Sykes, and intel agent Sophie Heisenberg in an emotional adventure, full of "witty" combats to thwart Akashian invasion.

For the cover, credits to swd3e2 on Pixiv!