First of all, congratulations on releasing the demo! It was certainly interesting.
After reading the notes section, I must admit I'm left a bit frustrated. It is clear that you have all put your hearts and souls into this - and that's to be admired - but I'm afraid I just didn't feel the love between characters. You say the idea was to endear them to the reader, but the demo was entirely too short for that. By the time I was getting around to remembering everyone's name, it was over. There was the "mom", the little star (boy? girl?), that sailor girl who was in love with the mom (why? how? when did they meet? why do I care? give me a reason to care!) and that purple haired girl who was... evil, for some reason.
As for the mystery, I'm quite curious about who this Leannan is and what happened to them and why they died. That chapter was a nice bit of writing and I'm looking forward to the full release to find out more.
Looking beyond the story, I really enjoyed the soundtrack - it fits the mood very well. On the art front, the sprites look very fancy and polished, nice work! If I have any complaints about the visuals, it's that the game feels entirely too busy, too cluttered. The backgrounds and sprites are all very colorful (perhaps too colorful) and they draw the reader's attention away from the main content, the text. At least switching to adventure novel mode helps a bit by getting rid of the fancy looking frames from the text boxes. For the demo's short duration it was tolerable; I forced myself to focus on the text and ended up mostly enjoying the story. But if this was a full length VN I know I would have given up long before the end. Most visual novels tend to focus too much on the novel and too little on the visuals; it felt like you have taken it too far in the other direction.
Still I did enjoy my time with it and I really am looking forward to the full release. Keep us posted please :)