That's Wakame, a character that esuyuki based on Emiri. It's basically a cat with Emiri's hairstyle. There's also Nyauko, which is the same deal but with Ryoko hair, and there's also one for Yuki, not sure what it's named though.
Wakame tends to show up or be sneaked into a lot of comics Esuyuki does, whether completely inexplicably as in this comic, or as a stuffed toy or a picture in the background or on a mug or something.
Uuugggh...She's gentle, and graceful, and pure, her voice is so cute and bright...And her charm points are...Uuugggh...Haruon! Extra chapter 06She's even good at cooking...she will become a great wife......thick eyebrows and a knife...?She smells so sweet, her perfume is relaxing...