As someone that now owns this doujin, its Flandre running in. I can't read the runes and haven't scanned this so I can use OCR and translator aggregator on it, but if I had to guess from context the rain was Patchouli's doing to keep Rinnosuke there. Just my guestimate.
So, have you read this book?Prepare a room, Koakuma.Sorry about that. Allow me to accept your kind offer.If you've any impressions, I'd like to hear them.
Ssshrrrr...
If you're worried about going home, there's no need.Stay here for the night.
Aye-aye, sir!♡
Don't trouble yourself. We've far too many rooms to spare, anyway.