The "mystery" is introduced when Mayaka and hear a ghost story from Rie Zenna. According to the tale, a guest once committed suicide by hanging in Room 7, and since then, frightening shadows have been seen there.
The episode's title refers to the proverb that "a ghost, upon examination, is just withered tall grass" (or in this case, withered flowers/dry clothes). It highlights Houtarou’s cynical but accurate worldview that most "mysteries" have mundane, human explanations. The episode is also noted for its intimate POV shots that pull the viewer into Houtarou's perspective as his feelings for Eru subtly begin to deepen. Hyouka episode 7-8 KyoAni comments | Ultimatemegax's blog Hyouka Episode 7
Despite his state, Houtarou applies his deductive skills to the "ghost." He eventually discovers that the hanging figure was not a spirit at all. The "mystery" is introduced when Mayaka and hear
Houtarou realizes that Rie had hung her sister Kayo's yukata in the room to dry because she didn't want Kayo to find out she had borrowed and stained it. Rie used the ghost story she had heard to scare people away from the room so her secret would remain safe. Thematic Meaning Houtarou realizes that Rie had hung her sister