This is actually quite a pleasant experience and the simple but effective narrative and set pieces you've put here actually gave me goosebumps when I reach level 3.
The good:
Gameplay just feels good. There is an interesting mix of classic SHUMP and classic touhou bullet-hell gameplay in this mix. Shooting feels great and mowing down enemies is always fun.
The theme doesn't really fit well but everything else is quite the treat.
To improve:
I am very, very interested in the way you do health system in the game and would love to see you try to innovate on it a bit more. Unlike SHUMPs and Bullet hells, getting hit is not fatal or disastrous and the player can actually tank a lot of hits.
I see you also adapt the bullet patterns to be extremely fast and aggressive to reflect this health system which I L.O.V.E.
I would love to see you expand on this kind of bullet pattern and health system more. Maybe reduce the efficacy of the vampire mode (dont make it heal to full because its too easy at the moment), and make much more rapid-fire, lightning fast bullets that is not always neccesarily dodgeable.
Very interesting honestly! A great take on the typical SHUMP/bullet hell genre! I honestly enjoyed it a lot.