User blog comment:B214/Volume 23 discussion blog/@comment-31137559-20170410191626/@comment-10330822-20170411020316

Exactly, and it certainly helps that Roygun seems to be a cougar anyway. Also, Issei is a dragon so he may in fact be ageless after he reaches his prime. This may go over well with Roygun because it means Issei will be permanently young.