@deedet for clarification, Asanagi is the illustrator for the Light Novel, as you can see in the cover image here, since it belong to the
Light Novel vol. 1 and not the manga (it was just put as default since manga don't have any image to put as cover, since there is no volume yet), the artist for the manga is Shibata Tsubakuro as is shown here under artist and official site web-ace, tho Asanagi is credited as character drafter/original character designs, since he did the original designs for the Light Novel and Tsubakuro is doing them based on those drafts too to keep it more faithful to the designs in the LN, as for what is Asanagi gender, for what i know he is male (based on what is listed in mangaupdates too)
TLDR, the cover image is just confusing people because asanagi name is on it (beside similar art in manga), but the cover image used here is from the light novel where he is the illustrator for and not the manga, in which the artist is tsubakuro, and tsubakuro is just drawing based on asanagi drafts since he is credited for that