The events depicted in Himatsubushi-hen occur five years before those portrayed in the previous three chapters. Unlike the initial chapters, which are narrated from various perspectives, this chapter is told through the eyes of Mamoru Akasaka, a young detective from Tokyo who travels to Hinamizawa to investigate the kidnapping of a politician's grandchild. As he delves deeper into the case, he finds himself drawn into the enigmatic world of Hinamizawa and its inhabitants, particularly Rika Furude, who becomes central to the mystery at hand.