She spawns lines of bullets from the side of the screen in a specific pattern, that being middle, diagonal starting at the top-left, middle, diagonal starting at the right then repeat.
The bullets are spawned, move into position, pause, and shoot themselves at your current location.
But I have a question of my own too:
How do I dodge the enemies after the midboss in SA's extra stage without dying/bombing? I see everyone spinning around the enemies, but I always die when I try that so I figured I must be doing something wrong. I just don't know what it is. So, I included a replay so hopefully someone can tell me what I'm doing wrong. Apart from not bombing on Koishi and dying almost every spellcard, but that has a different reason.