Definitely, Nujabes' beats also came up to my mind when playing your game, haha! With the theme you're aiming for, I am sure there'll lots of people who like it, I am one of them. Make sure to include the defiant character in the demo (sometime in the future builds) to make the game overall stronger!
I see.. so the beat decreases when you get hit.
Current game's difficulty is totally fine! I am playing the normal difficulty and it's manageable. I usually like to play on easier mode in a story-rich game. So, there isn't much necessary tweaking here.
What I meant by Kiro being disrespectful is just in general sense people are expected to take off their hats inside buildings (maybe it is only a me thing?). Especially here, Kiro is trying to learn from a master, wearing an especially wide hat just shows that he may be hiding something. So it just feels disrespectful to Matsumoto.
Good luck on the development!