User blog comment:B214/High School DxD EX/@comment-50.139.232.230-20150817033407/@comment-26209278-20150817160314

I'd assume it's because he's her subordinate, but im not sure. I don't know enough about Japanese marriage customs. I did 3 minutes research and read somewhere that a family with no son (with Sirzechs now being Lucifer instead of Gremory) that the son can adopt their name, but I dont know if thats right.