Cool idea for a game, it's not often you see a visual novel as the entry! I think the controls could have been conveyed better; for example, the "Continue" button that's mentioned on the blackboard (which can be interacted with, but it doesn't look like anything tells you that) is Enter, but that's not mentioned anywhere. Also, during the investigation phase, there was a "New Text" UI box that didn't go away, and when I tried interacting with the blackboard again, I just saw a bunch of square prompts and didn't have the right context to solve the mystery yet. It also looks like a screen resolution issue, as I think more prompts showed up on the right side off camera.
The art looks really good, well done on that! Though I think it was a bit weird that the female characters had the exact same portrait, but one was green. And the music sounds good, but feels a bit weird in the beginning when nothing tense has happened yet.
Again, really cool idea, and I would love to see this expanded out into a larger polished game. Good job!