I'm gonna guess they're the two remaining Hatsuharu-class (Ariake and Yuugure) who were in the same DesDiv with Shiratsuyu and Shigure. (I hoped it was Scathach, but the gradient hair says otherwise.)
I'm gonna have to agree with wataru kun. The girl in the background is almost certainly Kisaragi. Tag NOT added, because I'm not 100% certain (although if someone else adds the tag, I won't remove it).
The girl with the blue bikini will probably never be tagged. All we can discern is that she has neither a tan nor comically large breasts, and she probably does not have long hair (so not Akagi or Kaga)
Should we add Ariake as well? it is very apparent the girl in background to the left of Yuugure is Ariake although I cant really tell how but I'm pretty sure it is her with that pose she did.