Kaya's father is Shizuo Sato, an ordinary company employee who works as a white-collar salaryman. He is a devoted and caring parent who has assumed the primary responsibility of raising his daughter. Because his wife, Mirai, is nearing childbirth and experiences physical difficulties, Shizuo takes over the daily duties of taking Kaya to and from kindergarten and handling all the housework. His personality is defined by his dedication to his family and his hardworking nature, consistently striving to be present for his daughter even when his job demands long hours.

Shizuo's primary motivation is the well-being of his family. He works to support them financially while also managing the household to care for his pregnant wife. His role in the story is to serve as Kaya's primary guardian and the central figure in her home life. Unlike his daughter, Shizuo has no spiritual power or psychic ability whatsoever. He is completely unable to see the malevolent spirits that Kaya fights. This lack of spiritual awareness often puts him in difficult situations, as he can misunderstand his daughter's actions and is even at risk of becoming possessed by ghosts without ever realizing it. A key scene that illustrates his ordinary perspective and caring nature occurs when a lost elementary schoolgirl runs away from him and Kaya; Shizuo has no idea that a supernatural threat is the cause of her fear, but he still attempts to help her find her way to the police and later reunites her with her mother.

His most significant relationship is, of course, with Kaya. While he loves her and is a very present figure in her life, he cannot see the spirits she battles, creating a fundamental gap in his understanding of her daily experiences. He also has a close relationship with his wife, Mirai, whom he supports during her difficult pregnancy. Viewing episodes of the anime from his perspective reveals the human, everyday challenges of his life, showing him navigating parenthood and his job without the knowledge of the supernatural world that his daughter inhabits. While the story focuses more on Kaya's growth and her battles with spirits, Shizuo's development is more subtle, rooted in his consistent role as a reliable and hardworking father trying his best to hold his family together during a period of change with the impending arrival of a new child. He possesses no special abilities or combat skills, his strengths being his steadfast reliability and his commitment to his family.