Mutsu Ebisumori is the grandmother of Kaya Sato and a central figure in the family's spiritual heritage. She serves as the sixth generation Ebisumori priestess, making her a firstborn daughter of her generation just like Kaya. Mutsu is widely recognized as one of Japan's elite psychic mediums and is revered as the most powerful esper of her time within the occult field. Her abilities are formidable: she possesses eyes that can see the future, and in the past she has assisted the police with supernatural incidents. She is also known for performing exorcisms and using protective talismans. Mutsu's reputation and power cast a long shadow that Kaya must live up to, yet their relationship is complicated by the fact that Mutsu was initially unaware of Kaya's existence, having not been told of her daughter Mirai giving birth. When Mutsu first meets Kaya, she reacts with shock and alarm, suggesting that she perceives something terrible tied to the girl. Mutsu's role in the story becomes a tragic turning point: during a confrontation with Mirai, who is brewing a monstrous curse, Mutsu uses a protective talisman to save her other daughter Nana from a lethal blast of curse energy, dying in Nana's place. Her death serves as a catalyst for the final revelations about the dark secrets of the Ebisumori family.