This actually happened the same day as the last journal entry: I found the origin of that cat girl image. Go figure.
What happened was I Googled the "水紗姫" bit while keeping the "Kingdom of Chaos" angle in mind and came across this blog. It had the name and the green-haired image from the last post, and more importantly, a name. "Icon-Copylight:かや". I figured this "かや" was somewhere along the long list of links, and thanks to Wayback Machine, I found this, the smoking gun. Among the gallery up top was this image, which had a matching artstyle, including very similar skin tones, and tongue color