User blog comment:B214/Volume 22 spoilers/@comment-78.88.30.77-20170223181740/@comment-31137559-20170226010408

It would ruin the harem them. That's like wanting Grayfia to be in Issei's harem. And she is the king of her own peerage. Absolutely no reason or possibility of her being Bina. And she is most likely competing in the tournament with her peerage.

And if Bina is a Belial, then I think she would be the daughter of Diehauser Belial and one of his mistresses. That's assuming he has children and that he has a harem.