SPEC: Zero

Saya Toma was a high school student when her parents and younger brother died in an airplane accident. Detective Akio Kondo later informed her that there was a high possibility they had been killed by individuals who possessed "spec." This was the first time she had heard the term. Six years later, still haunted by the detective's words, Saya decides to become a detective herself. After receiving training from the FBI in the United States, she returns to Japan and is assigned to investigate unsolved cases in the Public Security Bureau. Meanwhile, due to a scheme orchestrated by Satoshi Chii, Juichi Ninomae comes to view Saya as his parents' enemy and attempts to drive her to the brink. Chii's plan also causes Saya and Juichi to forget that they are siblings. The two are drawn into a life-threatening confrontation. A girl named Maho Ueno becomes entangled in their conflict, and to protect her, Saya Toma begins to use "spec."