Well apparently it’s a game in unity, not very complicated although I couldn’t understand anything because it was all in Japanese or Korean hehe.
you should use https://github.com/BepInEx/HarmonyX similar to how mage kanade does. and do some kind of unpacking. or decompiled. or maybe something to see the game memory in real time. unfortunately I don’t know anything or very little about how to do that.
but if you investigate in that line, you will surely reach a good port. because I understand that it is how other unity games like onyx or max the elf were modded
check these projects that use these technologies that I tell you and they are integrations that worked
https://discuss.eroscripts.com/t/detaild-deselmine-mage-kanade-s-futanari-dungeon-quest-edi/110822
https://discuss.eroscripts.com/t/game-integration-pure-onyx-buttplug-intiface-integration/108156/
https://discuss.eroscripts.com/t/vibrator-support-for-6-action-and-platformer-games/97671