Hashiarai

Hashiarai is the annual washing of Nihonbashi Bridge, a July ritual that becomes a potential source of evidence: the crowd gathered around the bridge may have been captured in photographs taken by spectators, not just by the police or event organizers.

Ritual and Setting

The event consists of a water truck spraying the bridge while people scrub it with brushes. Its scale is visible in the many images Matsumiya finds online: crowds gather on and around the bridge to watch. Hashiarai is thus both a recurring civic activity and a conspicuous public occasion, drawing enough spectators to create a substantial photographic record.

From Event to Investigative Lead

When the investigators distinguish the bridge washing from a separate yukata festival, Fujisawa identifies Hashiarai as the larger July event. Kaga recognizes it and responds with sudden interest. After looking over the images on Matsumiya’s phone, he proposes contacting everyone—professional and amateur photographers alike—who has photographed the washing. The images already circulating online suggest that the search could reach far beyond official records.

Evidentiary Significance

Kaga’s reasoning shifts attention from the bridge itself to the people who came to see it. A visitor might appear incidentally in a photograph taken by another spectator; collecting images from many sources could therefore expose a face that no single photographer deliberately documented. Hashiarai’s importance to the investigation lies in this gap between a public ritual and its unintended visual record: the crowd makes the event large, but also makes it possible for a witness to have been photographed without knowing it.