Shingo Sumeragi is a police detective in Kamaya City. Years before the main events, his wife Shiori disappeared, leading their daughter Matoi to be raised primarily by Shingo's parents. Shingo only recently reunited with Matoi, who moved in to live with him approximately three months before the incident at Tenman Shrine.

The attack on Tenman Shrine, injuring the Kusanagi family, triggers Shingo's investigation. During this case, he apprehends a disturbed individual who becomes his sole witness. This apprehension coincides with the ritual that inadvertently grants Matoi divine powers. Shingo remains unaware of Matoi's transformation or her new role combating evil spirits. His police work often involves investigating the same supernatural disturbances she battles, creating an indirect conflict where his efforts to uncover the truth risk exposing her secret activities.

The shared trauma of Shiori's disappearance profoundly impacts Shingo and Matoi's relationship. Their initial interactions are marked by emotional distance and the struggle to rebuild familial bonds after years apart. Shingo's demanding work schedule and their unresolved grief contribute to this estrangement. Witnessing the dangers unfolding in Kamaya City fuels his protective instincts towards Matoi. He deeply desires to shield her from harm and improve their communication, reflecting his underlying care and commitment as a father.

As events unfold, Shingo actively works to bridge the emotional gap with his daughter. Their efforts to reconcile and understand each other intensify just before the final battle against the primary antagonist. This shared adversity provides a catalyst for emotional healing and strengthens their bond, offering them a sense of closure regarding their past struggles and Shiori's absence.