It's almost time in Hinamizawa for the Watanagashi Festival. In this arc, the tradition is to send hina dolls down the river to wash away impurities, but every year one goes missing and the person who it represented will drown in the river in its stead. Mion has been going to prep school and returns to Hinamizawa for the festival to find she has no hina doll. She begins to feel paranoid. What will become of Mion?