Rad danmakugame. The sprites have a lot of polish and there's quite a few of them, given the timeframe. Kinda awesome that you added two more character sprites for one spell. The music was rad and the patterns were really-well done, with enough of them present to feel like a pretty substantial game. The final bosses' patterns were by far the best ones, but each boss had their own cool gimmick, and I appreciated how they all moved in interesting ways for at least one pattern. I liked the dialogue, though parts of it felt a bit too cheesy-- it's hard to explain and a bit rich coming from someone with my tastes in stories, sorry.
Like the previous commenter said, the lack of background changes between stages/nonspell portions was pretty noticeable. Even just a color change to the same background can go a long way. But at the same time, there's not really any location changes, so it's fine. Besides that, I kinda wish you had a slightly longer invincibility time after getting hit or switching characters, considering theres no bombs. Also, I think the visible player hitbox is too small. It's more accurate to the actual size of the hitbox than what the official games do, but even without the window being small I think I'd have to squint to see it, and at that point it's no help at all. Maybe making the player character's sprite smaller would solve it too. And one last thing, the characters seem to be paired up mainly because they come from the same game a couple stages apart, and while that's neat I'd have liked to see something a bit more out-there.
Okay sorry, this review might sound negative for all that flaw-listing, but keep in mind these are real minor nitpicks. The core game here is really good, and I admire how you were able to put so much danmaku in here.