Cheat codes are available to those who support the game on Patreon. But even without them, the game can be completed if you delve a little into the mechanics of the game. But many players are simply too lazy to read the small books in the library.
So? I don't want to support hentai game (even when the game is not bad). The thing is leveling up is boring. The moment when i wrote my comment was when i completed current story and all secret events. And the library was only usefull for elemetal weakness that's all i used it for. Like for real if you are stupid or lost you can ask either that woman or tavern guy, if you have problem with relationships you can buy the heart from one hooded woman. Other things in library also does not help you in any way. cheat codes gives you advantage in way of not losing more time that you want to that is the point of cheats and author of this game used everything to protect the game from cheats.