河童

1. Origins, structure, and basic meaning

• Structure: 河童 (かっぱ) is a Japanese folkloric water spirit. 河童が住む refers to the legendary being; 河童の面 is a mask representing its appearance.
• Basic usage: A pond legend says a kappa lives there, while a child at a festival wears a kappa mask.

2. Common pitfalls and similar expressions

• Creature in a legend and figure represented by a mask
  • The first example makes the being itself the subject. The second uses の for a representational motif, so the child wearing the mask is not literally a kappa.