In a mass of perverse tabs, saw work by Arnage of circle Sage, but can't pin down their presence here in posts or tags. Are either represented here, and should the Kobayashi Yuuji and Ryunnu wikis include the latter in the Group section? (Sorry, really unversed with artist tag management.)
Unrelatedly, post #1057965 was tagged with TNK as the artist, but post #1298207 of the same Pixiv is given under "tanakana". Haven;t looked up other images from that Pixiv to see if there's any other red tags.
EDIT: Digging around blindly, post #1478437 is shown at sol-fa-soft's site (2013/8/8) and the Sage entity (already in Ryuunu's wiki) is name-dropped there and the posts Pixiv page. If any of that may help cohesion.
Updated