Kurako Tsukikage [Codename: LUNA] is a covert special investigator who operates in the shadows to protect national secrets. Engaged in missions too classified to be acknowledged publicly, her true identity remains unknown to all. One day, she receives a special order from her superior, Chief Nagata: "Infiltrate a human trafficking syndicate's hideout and steal the data." However, the leader of that criminal organization turns out to be Nagata himself. Trapped in her superior's conspiracy, LUNA gradually uncovers the truth. In the process, she confronts the organization's rampant conspiracy and her own hidden identity. LUNA's relentless pursuit of the one truth in the darkness drives this story forward.