Only works if you use chrome and firefox, other browsers... find out how they request files from network:
Open game, press F12 for chrome, ctrl+shift+I for firefox.
Click on "Network". There's a bar named "Filter" beside the hide data URLs. Type in "_harem".
Open up your scene. You should see a file pop up (there's a lot of other files before this, but it should be the bottom one/ last one that appears when you open up the file. Right click, click open in new tab.
Right click anywhere in the new tab, where you see a huge string of words (that's the script btw), click "save as" into a folder with your character's name (or anything. You just need to recognise the folder in the actual player).
Transfer folder to "game">"nutaku".
Go back to "game", run download assets, then run "build rpy", finally run "write config". Don't touch anything until the program says press any key to continue in the meantimes.
Edited to be actually correct, thanks Eliont