High school student Saya Toma's world was shattered when she lost her parents and younger brother in a tragic airplane accident. Detective Akio Kondo delivered the devastating news that her family may have been targeted by individuals with special abilities, known as "spec". This revelation haunted Saya for six long years as she trained with the FBI in the United States before returning to Japan as a determined detective. Tasked with investigating cold cases at the Public Security Bureau, Saya's resolve is tested when she becomes entangled in a dangerous game orchestrated by the cunning Satoshi Chii. Unbeknownst to Saya, her own brother Juichi Ninomae is manipulated into viewing her as an enemy, pushing them towards a fateful confrontation. As the siblings grapple with their forgotten connection, a mysterious girl named Maho Ueno is drawn into their conflict. In order to protect Maho, Saya must harness the power of "spec" to face off against her own flesh and blood in a battle that will determine their fates.