@Drey @ramzy author (story) is the one from Mushoku Tensei, the artist for the Light Novel is Asanagi, but the artist for the manga is not Asanagi, is Tsubakuro (he is just mimicking Asanagi LN art to keep it more faithful to Asanagi characters designs somewhat)
@mrguest only connection the artist of the manga have with Asanagi probably, is that Asanagi do the art of this for the Light Novel lol, as is shown in the cover used for now in here, since it belong to the volume 1 of the LN (it gonna get changed once the manga get a volume anyway)
@UnieCetterie like i said to the others, Asanagi is there in the cover, because the cover used here is the one from the LN vol 1 (he is the artist for the LN), since manga don't have a volume yet LN cover is used as default, but Asanagi is not the artist for the manga (the group that translated chapter 0 put the ln vol 1 cover too, but that page is not in the raws tho lol)
Asanagi is credited as original character design/character draft, since pretty much the artist is doing the designs based on Asanagi ones (if the artist picked a different artstyle and designs, there won't be any need for that most likely)