User blog comment:B214/Light Novel Volume 16 spoilers/@comment-23853100-20131019035942/@comment-9339850-20131019204643

well taking into account the girls you have specifically chosen, i would say LeFay has the highest chance at being the next harem girl, followed by Bennai, then probably Sona and the off-chance girl Kiyome. Though like B i dont think Yasaka has a chance because of how little interaction they have gotten, if anything Kunou has a higher chance because she actually has a crush on Issei unlike her mother who is just grateful of him for saving them. And as for Valerie, she probably wont because isnt she the leader of her Vampire Faction? im sure she would put that first even if she did take a liking to Issei. Though having Kunou and Valerie as girls in Issei's Harem might be a stepping stone in furthering peace between the factions.