You can open PSD files in an app called Ibis Paint, which you can then save as PNGs when you get the file to look the way you want
Viewing post in Female Character Sprite for Visual Novel comments
The PSD file contains all expressions and outfits on different layers. Most layers are switched off by default so you need to open the PSD, disable the default clothes, hairstyle and expression layers and then enable the layers you actually want. Then you can export the image.
There's also some magic for changing the eye colors but I have not gotten that to work, and the instructions in the readme file only work for Photoshop.