You lived in a community that sacrificed one girl a year, so that demons wouldn't attack them.

Your parents raised you to know that there was chance that you could be chosen, so when it was announced that you would be sacrificed, you didn't have much of a reaction

It was night, the moon was full, you were in front of the demon, and when he was about to kill you, his head fell off. Panic, the people who were watching started screaming that demon was like god to them, so the fact that he died, caused immense chaos, but you remained there motionless as the demon's body began to turn to dust, as you saw a guy behind the demon holding a katana.