Ayumu Narumi, overshadowed by his renowned detective brother Kiyotaka, faces a sudden twist when Kiyotaka vanishes, leaving a puzzling note hinting at the enigmatic 'Blade Children.' As Ayumu grapples with suspicion in a classmate's death initially deemed suicide, he unearths a web of murder and deceit that implicates him. Delving deeper, he uncovers the sinister ties between the Blade Children and his missing brother, realizing their unsettling connection to his own existence.