gotta say, I adore the art style of this game - the cutscenes are really endearing too, it's very fun
I did find it a bit unforgiving with the instant death mechanic especially during the boss fight, I think the attack animation isn't quite centered properly so where you flip horizontal your attacks don't really line up properly - meaning I'd find it easy sticking to attacking while facing right rather than facing left and waiting for the boss to come to the other side of the screen
that being said, you did a great job!