not sure what to do with .rtex files

[classxio]

I've been trying to extract things from the PC game Jakou no Lyla, and while I was able to find a script to extract from the .memf files, the output files in .rtex have sort of baffled me again. Can't quite figure out the programs/scripts needed in order to get the .rtex files into a workable image file.

Sample .rtex file here, if anyone would need it. (Heads up this is something of a suggestive game so if this file is nsfw I'm so sorry, I can't see it to check it!)