For example, here are fun theories I've heard so far:
- Takae definitely has to be the culprit, because she talks slowly. Therefore, she is secretly a robot. Robots are evil, so she is the culprit.
- Yumi is the culprit, because there is something seriously wrong with anyone who likes pink that much.
- Rentaro is the culprit, because only a puzzle maniac like him would come up with so many puzzles for Nancy to solve.
- Miwako is the culprit, because she wants to quit her job at the ryokan and become a professional baseball player.