The parry is fun, and I like how only being able to deal damage with the parry encourages you to run into enemies' attacks instead of dodging them so that you can beat them faster. I do agree with Looey's comment though about how you can easily just stand still and wait for the boss to come to you.
The visuals and audio are pretty nice and polished. The simple color palette is used well here, though a couple times I found it hard to discern enemies from the background decor.
The jump was kinda weird. The trajectory felt more like a hover than a jump. You don't have to jump much during fights at least, and there wasn't very much platforming, so that didn't end up being a big problem.
Is there supposed to be a puzzle with the piano keys? There's an NPC right before that sings a melody, but it seems like with the notes available on the piano it can't be played. I tried to adapt the melody to the available notes in a few different ways, but none seemed to have worked.
The boss fights were cool. On the attempt that I beat the final boss on, I managed to do so hitless, which felt nice.
It lacks a bit in the metroidvania/exploration aspects, though that's to be expected given the combat focus.
Overall, this is a pretty solid entry. Good job.