Hanyu is the mysterious transfer student and distant relative of Rika’s. She has appeared to Rika her entire life, but mot until others started remembering previous Hinamizawa’s did she gain the ability to interact with the others.
Due to her spirit like nature, her appearance can change with her mood causing her to be very frightening when angered. Hanyu was the one who started the loop of repeating Watanagashi. She did so in order to save Rika from being murdered.
Hanyu describes herself as being “above man” after having been sacrificed to atone for sins. The villagers refer to her as Oyashiro, even Rika does at times when talking to others about her, but in reality Rika views Hanyu as more of a friend than a diety. It is revealed in Higurashi no naku koro ni rei that Hanyu was in fact one of Rika’s ancestors and she was sacrificed to atone for the sins of the village. Hanyu asked her own daughter, another of Rika’s ancestors to kill her to make the village a better place.