This game is so incredibly well done! It's clear that a lot of time went into making this as great an experience as possible, so I feel like I have to be quite elaborate with my feedback here.
First off, cool concept. Rhythm games have been done a million times, and it's quite easy to mess up something small that ruins the entire experience without even noticing. You haven't done that, and it feels really great to play. The art style is adorable, and the story is surprisingly engaging. It seems rather generic on the surface, but as you keep playing, you get more and more invested. I found myself thinking "What style of music is next", and upon seeing the Jazz figure, thinking "What the hell kind of animal is that going to turn into?" The more I played, the more invested I got in the story.
That fact that you took the time to add a "hub" as well amazes me. The story unfolds and you get closer to your goal, but your house gets updated as well, not only with pictures/medals of what you've done but with the animals you've rescued. That's such a nice touch that really goes a long way when it comes to setting itself apart and making the experience feel complete and polished.
I hope you'll bear with me here, and I hope you may even respond to this part, but it's going to get a bit nerdy. I love what you've done in terms of difficulty. This clearly isn't meant to compete with the likes of Dance Dance Revolution or Guitar Hero, or even Friday Night Funkin', this is clearly meant to tell a story while also playing/listening to some awesome music. You're not meant to be grinding for days to get a perfect score or an FC, you're meant to enjoy yourself. Not adding a fail condition (at least not from what I played on easy and normal), you allow the player to explore the game at their own pace, and the score at the end only shows stats regarding notes you did hit and also hammers home the positive and casual vibe the game has. There's no stat for how many times you missed, there's no "you missed too much, now you're dead", it's about experiencing the game, not perfecting it.
This helps set the tone for the game. Believe it or not, gameplay and art style aren't all that make a game feel a certain way, something as simple as choosing not to display notes missed goes a long way, too. I don't know if these things were intentional, but it really works with this game specifically. If your game had been about "dancing with the devil", I could see the game being a bit more hardcore, but when you found out that what's been barking up the wrong tree is literally a dog, you don't think of the word "hardcore". This way, the only real challenge is actually improving yourself. If there's a fail state, you beat the track, and you feel like you're done. When there's no fail condition, your own challenge is to beat your previous score, not just the boss.
One of the best entries I've played. Super polished, knows what it wants to do, and does it super well. You've nailed the mechanic and polished everything around it. You've also managed to set a tone and expectations from the player from the get-go. Super solid experience. Kudos to everyone on the team, you should all be very proud!