User blog comment:B214/Volume 23 discussion blog/@comment-77.188.219.183-20170424231130/@comment-79.25.167.4-20170425111052

I think he will be Issei Gremory, but the one who will marry into his family will have Hyodo's surname because he is not a Gremory by blood, I guess that's the reason why Robertina and Airi have his last name, while the other kept their mother's last names.