Nobita is in trouble when his mother finds a test paper he failed in, in his drawer. Nobita wants a lock so Doraemon gives him a key which can lock anything. Once done, only the user can open or shut it, using the words: Open Sesame or Close Sesame. The episode ends up with Nobita locked out of the house in heavy rain because he has a cold which has changed his voice so the key no longer recognizes him.
| Creator | N/A |
|---|---|
| Actor | Nobuyo Oyama, Noriko Ohara, Sachiko Chijimatsu |
| Country | Japan |
| Production | Shin-Ei Animation |