User blog comment:Crimson and Darkness/Volume 25 discussion blog/@comment-95.210.189.106-20180512100239/@comment-41.13.8.62-20180512105754

Head of ExE will definitely happen. But Maou i also dont like that idea. However Grayfia did tell Rias that eventually the people of the Underworld will want Issei to become a Maou so that is very likely to happen.