why do you still need to peek when you already married her?
Seeing that Shigure didn't have her hair flaps (and her Kai-2 form), that scene can only be when Shigure was taking a bath with Shiratsuyu and Murasame in the anime.
Ohooo!I knew it, Shigure is the best!!Small ones are also cute♥Was inside the dock (here)