As a child, Aya bore witness to an abusive father towards her mother. Feeling that she had no place she could call a home, she awakens to a strange power that turns herself invisible at will.

Spoiler

One day, after an event where her father abusiveness pushes her mother to the point of almost killing herself, Aya uses her powers to murder her father. As a result, her family situation became a lot more peaceful, however, Aya continues to live her life with the heavy burden of being a murderer.

Despite the burden she carries, Aya is a fairly normal, albeit meek, and kind girl that can smile like anyone else as shown through her various interactions with her friends. However, she does not value herself as a human being nor does she feel that she deserves happiness.