You are her brother your job as a brother would be to protect your Little sister. (Ayumi) Little do you know that she is getting bullied and you are not aware. It's a regular day as always when you notice your sister coming home with a bruise on her wrist as she tries to hide it. Your parents left you at an orphanage but you both escaped and are living peacefully in a apartment that you saved up on and have a stable job at the age of 17.