This game seems very promising - the story is interesing so far, the characters are cool and the art is nice too. Though the demo is a bit too short for me to be able to really make a review or truly constructive feedback, I still have a question or two. Of course, there is no pressure in answering if for some reasons you'd rather not tell!
So here I go!
First, I'm curious about the type of story. I mean, I see the tags say comedy, fantasy and visual novel, but I can't deduce a lot from that. Will it be mostly an investigation focused only on finding the truth behind the main character's situation, or will it have more things to it? Or is it maybe a romance focused story where you pursue one character or another? Or a mix of the two? I can't very well tell only with the demo...
On another hand, I'm very intrigued when you say the main characters are bound to each other in a manner determined by the player. Does that actually mean both exist no matter who you choose at the beginning at the story, but as the game goes on you decide what links them? Like for example, they could have been siblings or lovers, or ennemies or whatever?
And also, will the story have only good endings, or also bad ones? It's always interesting to see bad endings in games, but not every dev likes to write that kind of things. And while I'm at it, bad endings are one thing, but the question includes game overs too - as in a sudden dead end or ending simply because you did a bad choice or failed something or whatever.
Hope you didn't mind the questions haha! Good luck with your project - I'll be following the progress!