User blog comment:IamJakuhoRaikoben/Chapter 467: Mother's Key, Review./@comment-24499036-20160108052604/@comment-26042226-20160108193241

I'm pretty sure that Dan is an anime-only character, I personally have never seen Dan in the manga or a mention of him, however, when/if they animate Alvarez they could make some sort of link between the two. So as far as the manga goes, nope. But we'll have to wait for the anime to get to where the manga is at right now