Himatsubushi-hen takes place five years before the previous three. In contrast to the first three chapters, this chapter is shown through the eyes of Mamoru Akasaka, a young police investigator from Tokyo who comes to Hinamizawa in order to investigate a kidnapping of a politician's grandchild. Soon, he too becomes implicated in the mysteries of Hinamizawa. This chapter focuses on Rika Furude as being the key part of the mystery.
(Source: Wikipedia)