Does this game really have monster girls or is that tag misplaced? I hope the monster girl is a succubus.
Considering the questions you have been asking, perhaps you need a more detailes response.
1) There are plenty of monster girls, but 95% of the time they are in their human form. You need to develop your relationship with them for them to show you their "transformation"
2) The society presented in the game consists of humans and monster people (called Mythics), who hide their true nature from the humans. This means that some characters are Mythics and some are human, but there are also half-mythics (people who are children of a human and a mythic - they get to know about mythics but are basically just human - no powers or anything). There are currently two of these in the game: the MC and Aliza, who works in the library.
3) The need to keep their nature and powers a secret, means that in some cases it takes time before a girl reveals that she is a mythic. For the same reason, the MC cannot just keep hitting up girls and telling them "Hi! I'm a half-mythic, so if you are a mythic, it's totally ok for you to tell/show me." As a matter of fact, the trope of a girl accidentally revealing her nature to the MC and freaking out over it for a monemt (before being calmed down with MC telling them he is ok to know), is used several times in the story. I would say that it works considering the world they live in, but then again... if he wasn't a half-mythic, there would be several fubars commited by clumsy chicks all over this weird town...