First of all, I love the art style of the game. The backgrounds and effects look amazing, and the lore is fantastic. I wish it was implemented more in the game!
The boss design was also really cool. The first boss was tough, but it felt satisfying to crack.
My only significant concern is with the special attack. I feel that adding feedback to let the player know when their special attack isn't available would be beneficial—perhaps a sound or a visual cue. Alternatively, you could consider allowing the player to start with a special attack. This is to avoid confusion, as you show the Special Attack button on the controls in the first scene, but pressing it seemingly does nothing.
That said, I enjoyed what I played and I look forward for more!