I was in Tokyo for a holiday and I just came back to the hotel after some sightseeing. I wanted to go back to my room but I couldn’t find my key anywhere. Then I remembered I left it at the key place when I left the room in the morning. How do I tell the staff that I’ve forgotten my key in the room in Japanese?


Answer by Professional Japanese Teacher
Heya ni kagi o wasurete shimaimashita.
I forgot my key in the room.

Heya is “room” and kagi is “key”. Wasureru is “to forget”. You can say “wasuremashita” (I forgot) but “wasurete shimaimashita” conveys an additional sense of regret.

It means something like “I shouldn’t have forgotten the key but I did and I’m sorry for the inconvenience”. You can add “sumimasen” (sorry) in front to emphasize your apology for the inconvenience.