After becoming an investigator, Saeko vows revenge against the mysterious "Skull Man" who violated her and begins taking action. However, during a mission, she commits a serious mistake and is arrested. Before her stands the notorious "Skull Man," rumored to be the mastermind behind the organization. His true identity turns out to be a shocking figure Saeko never expected. The story takes a dramatic turn as revenge, truth, and the threads of fate intertwine.