Just FYI, according to the Pixiv description, they're eating fried pasta(?!), and in the comments, the artist insists that the reasoning behind which characters were selected is a secret.
Alice doesn't have a midboss in her Perfect Cherry Blossom stage. Patchouli has Koakuma. Nitori doesn't have a midboss in her Mountain of Faith stage. Marisa doesn't have a midboss in her Imperishable Night stage. Sakuya doesn't have a midboss in her Embodiment of Scarlet Devil stage.
Alice: The only one have a flan in front of face Patchouli: The only one have a mid boss Nitori: The only one not appear in fighting game Marisa: The only one smiling Sakuya: The only wearing PA- *Stab*
Alice: The only one have a flan in front of face Patchouli: The only one have a mid boss Nitori: The only one not appear in fighting game Marisa: The only one smiling Sakuya: The only wearing PA- *Stab*
Now that Nitori have appeared in HM, I propose the following corrections for Nitori and Sakuya: N: The only one not to appear in IaMP S: The only one not to be 'playable' in SA