The Atomic Punk
At first, I was thinking just a shy schoolgirl. Then I listened to Mozart’s Dies Irae. Epic! Your anime style inspired this opening scene.
Here is how I envision the rest. The main protagonists are Sibyl and her classmate David. Sibyl is psychic. David is a normal teenager. The two survive the fire that engulfs the earth. They seek answers to the cataclysmic event. They explore the new world that rises from the ashes. Appropriately called Aschewelt (“Ashworld”, which is also the title of the anime series).
Aschewelt is populated by what might be considered demons, mutants, or aliens bent on destroying the human survivors. Haven’t decided on any specific term or species. Nonetheless, these are powerful beings with abilities and themes inspired by Greek mythology. Sibyl is a prophetess in Greek antiquity. Sibyl the schoolgirl becomes more powerful as the classmates encounter more monsters. David becomes a capable fighter in his own right. Sometimes, he gains temporary powers through various magic, artifacts, or alien technology.
Of course, Mozart is the background music to all of the action.