(Achievement title formerly known as "Hated by All Women")
"Did all the naughty things in the dressing room."
That means while you're in the Dressing Room you need to do nearly every piece of interaction to one girl of your choosing.
Try what you need to do in one go without exiting the Dressing Room in case it may reset athough there seems to be some confirmation of this being unnecessary.

The girl needs to be wearing a loose skirt at some point so for this I chose Homura's Shinobi outfit from beginning to end just to be safe although I'm pretty sure that so long as you don't switch characters the interactions you make would still count, but that may be unnecessary as well.

Unlike the original Vita version, there are fewer things required in order to unlock this.
If an interaction to the girl has been done correctly she should make a response, usually just in the form of small dialogue. It's probably easier to enter the character viewer's fullscreen mode so you won't have to deal with the Dressing Room's menu. The requirements needed doesn't need to be completed in order either but it might help to be organized.
Because some interactions give off responses that are far too similar to one another it'd be best to play it safe, like try flipping the skirt from both sides instead of just from one and poke both sides of a girl's pelvic region.