User blog comment:B214/Volume 22 spoilers/@comment-82.48.158.172-20161109231053/@comment-10330822-20161111014017

Issei may have a mutation knight for all we know, we aren't sure at this point.

Plus, when you think about, Issei's peerage already has really powerful pieces, meaning that he can't just get anyone to fill it out, he doesn't have the time to build people up like he was, it would be a step back for him. Taking a Longinus user or a Pureblood Vampire may be better than just starting fresh.

Part of me felt like he may make Kunou a pawn, even though she is the young leader of the Yokai. I feel she would be good for the diversity of his peerage.

Yura may be an alternative, but I feel her character kind of conflicts with Xenovia's, they are pretty much the same people, even down to the hair. The only different is that Yura is more physical while Xenovia uses swords. You are better off with someone who is very different to the characters he already has.