While I'm not a visual novel expert, I can tell a lot of love and care went into this demo.
First of all: The art is gorgeous! The several backdrops are well crafted and really create atmosphere. The characters are drawn really nice aswell, especially the non-human characters. Finally, I really dig the look of the ui and menus, they're simple, yeah, but in a professional looking way.
The music was also a pleasant surprise. From the moment you boot the game up and hear the calming, yet forboding, title screen music until the tense moments. While I won't listen to it outside of the game, It is generally very pleasant to listen to while you enjoy the story.
speaking of the story: I find the writing decent, although I found a few typos during my playthrough.(I was playing the english version) It's good enough to hold my intrigue and I'm looking forward to what you make of this game!