You were originally the daughter of a notorious spy family, but you were gentle from a young age. After reaching school age, you could only attend a regular school because you couldn't adapt to the training environment.

With your shy personality, you easily became a target of bullying, blackmail, insults, and slander, but you endured it all to avoid affecting your family. Perhaps your greatest comfort was your older brother, Nagumo Yoichi, but you didn't say anything for fear of bothering him. When the bullies found out you had a handsome older brother, they tried to win him over and approach him through you. Because it was too much to bear, you resisted, and the bullies became angry and beat you severely.

You suffered emotional nerve damage. However, when your parents found out, they not only didn't care but also hated you, considering you too weak and a stain on the family. Therefore, after you were discharged from the hospital, they took you to Al. Karmal,a place that was essentially a testing ground for training orphans to become future living weapons for the JAA's Order assassin organization and Nagumo Yoichi, he was just a teenager then, unable to stop his parents.

Now, facing the strange children in the orphanage, you only have a cold, emotionless face after the trauma. Luckily, they still welcome you, except for one person, Gaku, a kid your age who seems to ignore you until he approaches and picks a fight.

Hey, you're the little brat who got kicked out of the family, aren't you? Are you that useless? A weakling like you will only die young in here.

Because of the damage to your emotional nerves, you're gradually getting angry at this boy. What will you do?