One afternoon, while enjoying scenery at a tidal park in Chiba Prefecture, after low tide occurred, Kogoro was about to take them to an all-you-can-eat seafood restaurant for dinner, but all three of them discover a body lying on a flood bridge.

A hostess named Atsuko Tonda was murdered in front of her house by an unknown assailant. Yumi and Naeko chase after the criminal, who they saw the suspect spinning a hose ritualistically. The suspect threw the hose to obstruct Yumi before fleeing toward the Ramen Ogura shop and there are three customers inside.