I've just played it 1 time, Needle Reimu, normal difficulty. Tomorrow I will play it too, liked it.
Feedback:
1) Stage 1
1.1 Density (total amount) of bullets in preboss part of the stage looks low. Mostly, I'm talking about lots of free space on screen. Suggest increasing.
1.2 Reisen's spellcards look a lot like her non-spells. Suggest more "special mechanics" (like in that spellcard, last or prelast? where bullets "classically" disappear in certain area), and some bullet recolour/sprite replace (red circles, for example, if it fits the idea).
2) Stage 2
2.1 Density (total amount) of bullets in preboss part of the stage is OK.
2.2 Were 100% of bullets green-coloured? Good idea, but I suggest recolouring 15-20% of bullets into dark blue or black, it will fit the Bamboo forest background.
2.3 May I call the boss "Hedhehog girl"? :V
3) Stage 3
3.1 Kodamo girls, YAY!!!
3.2 Density (total amount) of bullets in preboss part of the stage is way too high.
Judging by gradation from stage 1 to 3, what will be on stage 6? Suggest considerable reduce.
3.3 Butterfly faires with purple-white large circles that spawn elliptic ballets should be nerfed. They are too difficult for this difficulty and this character, and make way too much walling (at the very beginning of the stage I was blocked to the death). I suggest 1.5sec-pause between each 4-6 bullets or smth like that.
3.4 Last spell of Boss - I was killed twice by the yellow sun before actually understanding what had killed me. :V The sun looked like the part of spellcard background :]
4) Total:
4.1 Liked the music, liked the 3D background
4.2 Liked the difficulty of bosses. Balanced just like specially for me.
4.3 Liked the spells, mostly.
4.4 Bullet density's gradation per stage should changed (more at stage 1, less increase with each stage).
4.5 Looking forward to the next update.