The girls shouldn't be surprised at all at this point.
I wish I could find a clip of it, but in the 1985 film, The Goonies, there's a scene where Chunk and Sloth enter a cavern where all the plumbing for the country club above them is all in motion.
And for a moment, Chunk just takes in all the chaos, and finally comes to a single, correct conclusion:
"Yeah, looks like Mikey was here alright."
Which should be the girls' reaction.
"Oh yeah. Haruka did this. No doubt about it."
Which oughta be followed by a line to the effect of, "Who pissed in his Wheaties this time?"