Something tells me it's Amatsukaze just reading the doujin out loud.
I think the punchline would be that, after Shimakaze finally mellowed and was willing to give Amatsukaze the benefit of the doubt, it turns out that nope! It really was that bad...
Honestly, I think the easiest solution would be to bang on the wall when she's doing it. Even if she only thinks someone is on to her it would probably set her straight. Maybe.
I-It's the truth!It's how it is!So it's not like she'd go around doing something so dirty, right...?I can't believe it myself either!But...She's so serious and handy and stuff...Amatsukaze, yeah?But y'know...W-What are you talking about!?Haven't you been listening to me?!Hah!?Is that really what's happening?Hey, Shimakaze...