The "ghost" was actually a yukata (a casual summer kimono) hung up to dry.
The club stays at an inn managed by relatives of , the Zenna family. While the rest of the group is excited, Houtarou Oreki struggles with his typical low energy and severe motion sickness from the bus ride. At the inn, they meet Mayaka's young relatives, Rie and Kayo Zenna . The Ghost Story Hyouka Episode 7
Eru’s intense curiosity is piqued, and she insists they investigate. Meanwhile, Houtarou is physically drained after a dizzying hot spring bath where he inadvertently lets his imagination run wild. The Investigation & Solution The "ghost" was actually a yukata (a casual