I love, love, LOVE the art style!! It's so cute. I also appreciate how the UI matches the art and how subtle and out of the way it is, which really lets the art shine.
The three culprits are all way too cute, my kneejerk reaction was to protect all of them! Seriously, I went in wondering if all three were gonna be innocent, even though I know that all three deal with breaking down organic waste in nature.
One suggestion: it would be cool to have some sort of inventory or notepad where players could review the evidence and clues they've found. I think it would make piecing things together a bit easier. When I was playing I found myself going back to different areas a few times to review.
That said, I managed to solve the riddle! Overall, this was a cute and fun game. Well done!