Nara Kenichi is a police officer who is tasked to investigate the disappearance of a 11-year-old girl Ishioka Aoi. It is not known if she was abducted, met with an accident or left home on her own because her parents were about to get divorced. Kenichi takes an exceptional interest in this case as his younger sister Mayuko has been affected emotionally since she was attacked by a man so he desperately wants to prevent something similar from happening.