Four years prior to the story, an assailant attacked Saeko. Armed with her bokken, she easily disposed of him, breaking several of his bones before the police came. Although it was claimed to be self-defense, this experience revealed her "raw nature". Ever since the incident, she continually struggles with this part of her personality, which causes momentary weaknesses in her otherwise strong demeanor. After telling Takashi her story and encountering a group of "them" afterwards, Saeko considers, for a second, letting herself get killed. However, Takashi stops her and confesses his admiration for her, restoring her confidence and resolve. After this, she accepts her true nature and promises to fight alongside Takashi. She also tells him that he needs to take responsibility for actions as a result of this, which he agrees to.
Voiced by: Miyuki Sawashiro (Japanese), Taylor Hannah (English)