The Morning Light and Hope After Dawn

This is a world full of bloody violence and darkness. Aliens invade the city and slaughter humans. Human beings are forced to build lines of defense and hide in the ruined cities, struggling to survive. This place was originally bleak and full of despair, until the appearance of a human girl brought a glimmer of light. Although it was as weak as a firefly, it stubbornly dispelled the darkness and brought light to the world. The long-lost light reappears, and hope once again breaks through the cage of despair. "The light is with you, may the holy light protect you." The girl who looked like a god under the sun lowered her eyes and whispered... Simple version: She appears with the first light after dawn, bringing light and hope to mankind. Later... She disappeared from the wasteland, taking the darkness and despair with her.