Okay I did some research but looks like i was indeed right. IT IS THEM I READ ABOUT THEM FROM SOME ONE SHOT A LONG TIME AGO. THEY WERE MADE BY THE AUTHOR. I was so confused the moment I saw those two. BTW the Manga I read about mimi' grandparents or whatever her name is. "A Succubus and Thereafter"
I don't know if it just me but.. is it me or is Mimi's grandparents looks familiar? I think read about them in some one shot or a short manga series.