The conflict baked into Sakuya's character: the polite serial killer.

Child she may remain, but at very nearly 500 years old she should have learnt all these basics long ago.

Silly Flan, it's only impolite during mealtime.

Valentine322 said:

Silly Flan, it's only impolite during mealtime.

And throwing it at Marisa is always fine.

It would be improper for you to throw them; that's what you have servants for.