Another ordinary day finds Houtarou Oreki at home, until his sister Tomoe convinces him to take a lifeguard shift at the nearby pool during the hot summer season. Arriving there, Oreki unexpectedly encounters the other Classics Club members, who are already busy discussing a recent mystery. Eru Chitanda spots a white item that had once rested on a woman's ear, now gone, sparking her curiosity about its sudden disappearance. Hyouka: Motsubeki Mono wa showcases Oreki and the rest of the Classics Club enjoying a relaxing afternoon at the pool while unraveling the mystery that has captured Chitanda's keen interest today.
