Full book reveals that it is Kasumi's cat ears headband, the weapon of mass destruction, Big 7's bane. Don't ask me why she has it.
Stop that, Michishio.Asashio!No matter how much of a pervert the opponent may be... right?You're facing off against a battleship...Some... something special..?Nagato-san, I'm well aware that you're not going to blab so easily.As a destroyer, one must show courtesy.OOSHIO!
THAT, PLEASE!!!Aye-aye!Yes, indeed.Shit...!!So I've had something special prepared for you.