Artist's commentary
August 9th is Hakurei Day!
Marisa: "Fwaaaaah~ so nice and cool~"
Reimu: "You're all annoying. Go back where you came from."
Nitori: "(But that's my electric fan you've got there...)"
is what it's about.
I know it's not just Reimu there (TN: despite being the Hakurei Day), but hey, it's Hakurei Day so play along (TN: counting them as a Hakurei).
Watch out for heatstroke, and I hope you all enjoy the summer.