So, first, I've gotta echo PersistentDreamer's points. Not being able to save is a shame. Tje items are such a colossal pain in every way that I think you'd best tear out that system and redesign it from nothing. I got the bug where the entire battle results screen is black apart from the floating orb, twice, and a similar thing also happened to me once when I paused. In the scene after choosing to choosing to tuck Joh in, the game went black.
Apart from that, I also think the game has problems with visibility and fatigue. The spritework is great, but I'll barely see it when my eyes are mandatorily glued to the top of the screen. The bars expanding like they're coming around a carousel is kinda neat but ultimately I think it would better to just have them stay one size. And not only is it half the screen away from the beautiful spritework, they're also as far away as physically possible from the health bars. Heave you considered making each bar (as well as the target zone) extend the entire vertical height of the screen? Then you could look anywhere up and down the screen - combo and SP at the top, sprites in the middle, HP at the bottom - without having to look away from what you need to be looking at.
Then the fatigue. Just give us a break of a few measures at a few points throughout the song to let us regain our composure and shake our fingers a bit, please? You could take that time to let one of the combatants say a one-liner or pull of a dance move if you don't want that time to be completely empty.