So, Basically I extracted the "renpyarchive."something something, and then used the original images and put them into clip studio paint (specifically any that had the main protagonist). Then I drew my OC over the image, using the same brush they used. Just a little light blending and adjustments then poof* there you go. Here's a link to the extractor you'll need, and remember to drag the archive file on the extractor.exe https://iwanplays.itch.io/rpaex
and here's an image reference