Kimiko is actually a talented seamstress and has put a lot of work into making cosplay outfits for Erika (and many others) over the years. This sketch comes from the trending at the time Kitty Keyhole undergarments that at the time just about every illustration being made featured. In this instance, it's a bit of a jest because Kimiko is helping make a grand ball gown for Komugiko for [spoilers] and she has this great idea to tweak the kitty keyhole into a fox shaped keyhole. Mugi is quite adamant that no one will see that because that dress is NOT coming off her. But maybe Kimiko knows (or mischievously hopes) better on things like this.
4 February 2016
Kimiko, Mugi, Yakugashi and Erika (in the background) from Megatokyo