AN APPLE DISASTER!!
That's the name of her song
And her name is Apple Girlington
She's the personification of
An apple

This spell card is called THE APPLE WIZARD OF MOUNT FUJI
It's part of important Japanese folk lore
The pre-battle dialogue goes like this:

You should taste my wonderful apples
No, sorry, I'm watching my weight recently
No!! You have to try the apples or I won't let you through!
Oh, well, I'll give you a diabetes won't I
[UNTRANSLATABLE JAPANESE IDIOM]

Then you have a weird chord change
Because it's a newer Touhou song

Then they make a joke about apple pie