Ah, I'm always happy to see PoFV characters (and bullets) in regular ol' danmaku.
Hmm, well, my first impression: "Oh my god, the background is white, the bullets are white, the player is white, I can't see anything!" It looks like in Aya's background you've zoomed in onto a cloud! Try changing SetGraphicScale(50,50); to SetGraphicScale(2,2); it looks a lot better! (Although the bullets still kind of blend into the clouds...)
Once Tewi's background comes in, I start to get a head-ache because it's going way too fast. That might be okay if it speeds up gradually (actually that might be kind of cool,) but when it's all of a sudden it's just too much. Also, I'm not at all sure if the background cutting part way is intentional or not. (It also looks bad, though.) Unfortunately, Tewi's card is also tragically easy.
The backgrounds get a lot better after the first two. Actually, I commend you for having different backgrounds for everyone. There are a few mistakes, but it was definitely the way to go. But anyways, Yuuka's card is the first one I liked, too. It reminds me of Mitori's first survival spell. Hmm, actually, with cards that make you spin around like this, it makes the most sense for them to be survival spells. Unless you're using homing bullets, they take forever to damage. Then again, if you had Yuuka take a break from time to time, it would give the player a chance to just shoot at her. It would be cool if the circle of bullets in the center broke up at that time, too. Anyways, I really enjoyed the flower bullets from PoFV; It's nice to see Yuuka using them again. (Although there seems to be some problem with the big flower's graphics?)
The rest of the spell are quite fun too. Reimu's seems impossible at first, but once you learn how to approach it it becomes a fair challenge. Komachi's spell is all about listening for the audio cues, and, well, I haven't gotten far in Shiki's spell, yet. Overall it's a good script.