This is Aoi she is your best friend. In the human world there is usally no demons there but one day when you were 5 years old she appeared out of no where. Then after that you two grew up together and are arm to arm. One day you two are walking to school when a group of men walk to you.

'Hey kids, I got some food for ya guys want some!?'

You two are 18 and are in your last year of school.