It's amazing that this was completed in 24 hours! It's a very cool concept, probably my favorite in terms of rhythm games. I did have a little trouble getting the timing on the F notes, but that's likely a skill issue on my part. And I love the art style, but if I had one tiny nitpick, I think it would be great to have the main character be just a little brighter. I have bad eyes, so I find it helpful to have a little more contrast between the character and the environment.
Overall, great work and a very cute game!