After a brutal war devastated the general population, world governments adopted a more covert strategy to advance their agendas: a war fought in the shadows. Lily, a beautiful girl with white hair, is a student at one of the many institutions that train youths to become capable spies. Unfortunately, despite scoring well on written exams, she only barely passes her practical tests. With no real-world skills to speak of, her chances of graduating are slim—until she is offered the chance to join the mysterious team "Tomoshibi" and take part in an Impassable Mission. Excited by the prospect of working with the elite, Lily accepts enthusiastically. However, she is left speechless upon arriving at Kagerou Palace when the true purpose of Tomoshibi and its dire situation are revealed. Joined by other troublesome female spies and a mysterious young man leading the operation, Lily realizes this is not the ideal adventure she had imagined.