I think, and it's coming from someone who despise visual novel, that it is a clever and interesting, well-document story that kept me interested from the beginning to the end.
The two protagonists were well-written and their relationship was believable, the actual plot was similar to Junji Ito stories (which I'm very fond of), and the choices really impact the story so it made me think I was really investigating the mystery.
What I don't like about visual novel is the lack of interesting visual, which help to emphasize the text. Your game has an interesting artistic direction and don't throw too much reading at once, everything is very digest.
I just think you could have gone further into horror elements, because it feels like the game end after much build-up, the mystery is "solved" before protagonist encounter real difficulties in their investigations. But maybe time limit was the problem here ?
I encourage you to continue the development of the game, I think you can make a greater mystery, more investigation mechanics, you have in fact everything to make a great game.