Crimson Whisper unfolds in early 1990s Tokyo, where Detective Naomi Ishikawa and the enigmatic onmyoji Shion Hoshizaki confront a string of brutal murders tied to ancient curses. As restless spirits rise and hidden truths surface, the two must face vengeance born from centuries of pain—where love, loss, and exorcism collide in a battle against the darkness haunting the city.