I've tried again to do my "dig up anonymous/unidentified artist" thing but came up empty handed and with no lead this time.

The only information I could surface based on my search is that this drawing had to have been inspired by kizakura art's mashup of Rim and Koko's Yatagarasu group outfit, basically Rim's hood and upper sleeve paired with the rest of Koko's outfit (might even be close enough to count as cosplay/adapted_costume/borrowed_design?) First seen here (and also here, both currently not yet uploaded on Danbooru as of writing this comment) in 2024-01-19, about two months before this post here got uploaded (2024-03-14).

I would be very grateful if someone manages to do better than me and get the artist properly tagged.