Decent rainbow shoot-em-up.
So first I'll say as a Touhou player, there were a couple scary things in there...
Like, during the stage section there were these lines of orange-haired fairies that, instead of vanishing into the bottom, slide along the bottom edge and towards my character, which made me panic. Same for these yinyang balls right at the start, they pop into existence at the bottom of screen with no heads-up, and there goes my life on my blind playthrough, it hasn't been 5 seconds. In official Touhou games the enemies don't just linger at the bottom of the screen, and if there are enemies spawning in the bottom, they can be actually seen coming - so again, I was really spooked.
The boss too has one scary thing, it's these amulet explosions in Spell 2. I don't know what's the deal with them but uh, panicc - they don't even have a hitbox but they were still very unexpected with no prior warning. Also in this same Spell 2, the actual explosions at bottom of screen - didn't not expect them, and why do these ones have a hitbox.
There's also the "coloured circles" that say "you're invincible"/"you died". I think you really should have a proper graphic for that. Not only does it really not look pretty, it also entirely covers your character AND enemy bullets. I don't think having an eyepatch that covers up the area of your character is any good for a player who tries to reposition themselves.
Scary surprises aside, the bullet patterns in there are a decent challenge. Maybe the stage section was too distracting with all its colours and how fast it scrolls, it makes the enemy bullets slightly hard to discern. But the game does look colourful and pretty.