WARNING this review contains major spoiler so I suggest you to try this out first and then read my review if you want to.
"Yup, its Zitta and I don't even need to look at the username. " and that's what's successful about the athetics here. Gameplay wise, the statsis mix up attacks, and the phase change (espeically when the boss goes giraffe) really caught me by suprise, they were unexpected but still feels fair, and understanding the extra works and time on designing under this is impresses me.
I would prefer more responses upon hitting the boss though, because I didn't even notice I was dealing damage before I'm like a minute into the game. A stagger, a short "oof", or even just a white flash on boss would do. The steps back is indeed a nice touch but when paired with the air slashing sound, it's even kinda misleading because I really thought I was missing those attacks.
And if you wanted to go an extra mile in Miyazaki-ness. I suggest making the charge attack manuelly released (so basically you charge as usual, but the attack won't be released until you release the key), so people would have to time it correctly to interupt with haste. That does adds a little bit of diffculty but it's going to raise the tention of battle even further in my believe.