[x] Try to convince them that this is normal in Gensokyo, and that fairies really aren't a threat to anyone. They should know better by now, but ….
-[X] Emphasize that fairies are all immortal, have poor memories and very little power. They get excited easily whenever a powerful youkai or magician is doing something, so your intervention would probably only draw in more fairies unless you disperse them all. Just enjoy the show, they don't mean any harm beyond pranks.
[x] If they're bothering your guests, you should do something about them:
- [x] Scatter the fairies, then wish the mermaid a peaceful rest of the night and return to your guests.
- - [x] If the mermaid asks, let her come meet everyone.