Selena has gone to the mall with local ninja/exhibitionist/voyeur Miyuki Shimada, and while they're there Miyuki dared Selena to strip down and streak across the mall rotunda. Since no one ever says no to a dare for some reason, Selena has done it, and returned, exuberant but bare. But her clothes are nowhere to be seen! (Except her panties, which are being held hostage.) This wasn't a dare, it was a prank all along!
Now as you may recall, on Selena's first day in town she happened to walk in on Miyuki first thing in the morning when both were completely nude. Now Miyuki thought that was pretty cool, and since there's been less nudity at home than usual - Lyta has been more modest than usual as an example to her little sister - Miyuki determined to see Selena naked again somehow. And she's succeeded!
Don't worry, she'll make it up to Selena somehow, probably by arranging an elaborate scenario where Selena gets her naked in return. Because Miyuki is an exhibitionist after all.
I mean, if she can lose that dress somewhere, both their Orange Julii will be free!