High schooler Yohana Sakaki lives in a town where ghosts, spirits, and other ethereal beings are commonplace. The powerful Yashiro family, a line of exorcists and spiritual administrators, holds absolute authority over the supernatural realm of the area. Yohana is a distant relative of the family, but she possesses no spiritual abilities and has resigned herself to an ordinary, uneventful life. That changes when her grandmother forces her to help at a banquet held at the Yashiro estate. During the event, Yohana accidentally falls into a pond on the grounds. The commotion draws the attention of a handsome high-ranking Yashiro heir, who approaches her as if she is his destined partner—only to lift out a classmate who fell in after her, ignoring Yohana completely. Left soaked and humiliated in the water, Yohana is rescued by a mysterious young boy named Chitose. Though he has little status within the Yashiro hierarchy, Chitose harbors many secrets. He takes Yohana to his secluded home on the estate and reveals that she is a marebito – a person who has gained divine power after drinking water from the boundary between worlds. As a marebito, Yohana is a rare asset, and the Yashiro family places her under their protection with Chitose as her guardian and partner. She begins assisting Chitose in his spiritual work, handling hauntings and malevolent spirits. As she grows into her latent abilities and navigates the complex politics of the Yashiro family, Yohana discovers that her encounter with the pond and her bond with Chitose have set her on a path that will reshape her destiny—for better or worse, no one can yet say. The story weaves together supernatural mysteries, folklore, and a slowly deepening romance between a strong-willed girl and a secretive boy who may be more than human.