玉手箱

1. Origins, structure, and basic meaning

• Structure: 玉手箱, read たまてばこ, means a mysterious box in a folktale or a box full of unexpected treasures.
• Basic usage: Use it for the story's object or figuratively for a box filled with mementos.

2. Common pitfalls and similar expressions

• Expressing a prohibition
  • The first example's 開けてはいけない means must not open. It expresses prohibition rather than inability.
• A comparison for a box
  • The second example's まるで玉手箱のようだ means just like a mysterious treasure box. まるで and ようだ emphasize the resemblance.