September 29, 2012 01:26 PM EDT
SHINee Key and KARA Nicole / Credit: SHINee me2day
Key wrote on SHINee's official Me2Day page on Thursday, "Nicole and bum's birthday party. It's really fun. Let's have a bigger party next year. Everyone come visit!" and included a picture.
In the picture he revealed, Key and Nicole are standing in front of a cake while smiling brightly.
Key's birthday is September 23 and Nicole's birthday is October 7, which is why they celebrated a joined birthday party. On various TV shows, Key and Nicole shared that they are very close since they are the same age, both born in 1991.