This is inspired by a few key covers I saw on Japanese websites. There was one site in particular (mentioned below) that I based mine on. Although mine is pretty different than that one too. I used felt and made it in the shape of a tag. And I used ribbon instead of a cord (because I didn't have any cord on hand). And I embroidered a bit of pink tulle in the shape of a heart onto it.
I don't know how the Japanese use these, but this could be worn as a "necklace" or around your wrist, or loop around your purse handles...or just toss in your bag.
(I decided to turn this into a tutorial...I'll post images to go along with it soon.)
Cut two pieces of felt into the shape of a tag. I used a tag I had on hand as a pattern, but you could just cut a rectangle shape and then snip two of the corners off.
If you wish, decorate the pieces of felt however you want. You could use simple embroidery, or sew felt pieces shapes onto it. On the first one I made I embroidered a heart and piece of pink tulle onto one side.
Stitch the two pieces of felt together. But leave the bottom open, and leave a small opening at the top that's big enough for the cord/ribbon to go through, but small enough that the key ring won't go through it.
Cut the cord to desired length and tie the ends together. Loop the cord around the key ring. .
Then slip the ribbon through the hole at the top and pull until the keys slide into their little cozy pocket