Normally, you would have chosen a swim-trunk or any other kind of swimsuit a man would wear. But not being any kind of magician, you don’t realize the stand is enchanted to make anyone using its wares choose a swimsuit for the opposite gender, nor that all swimwear he propose have a double-layer enchantment on them. The first so nobody will notice how strange it is for people of one gender to take swimwear for the opposite one, the second to change the first person wearing them change both physically and mentally to make them fit their new swimwear, without anyone noticing they even changed in the first place.
Neither are you aware the stand-owner is the kind of guy willing to steal any underwear enchanted in such a way to ensure he would be the one making other peoples wear them, not caring what their makers wanted to make of them.
Once in a cabin to change, you get out of your soiled trunk and put on the bottom half, looking like ocean-blue boy-shorts with a slight gradient, making them look turquoise toward the bottom, while the top as a large black stripe, proving its creator was really dedicated to mimicking boxer briefs. You don’t notice how it fit you snugly even though it shouldn’t but, to be honest, you didn’t even notice it was for girls, so…
Now you put on the top, which look a bit more feminine. It’s in the same mostly ocean-blue textile as the bottom part, with the same gradient making the lowest part of this top look turquoise. That’s the fabric used for the part supposed to maintain the boobs you don’t have yet. It is composed of two triangle, one slightly covering the other. To reinforce the kimono-like effect it can have, while also reflecting the top part of the bottom piece, a large black band, copying a kimono’s folds, is sewed on the inside border of a triangle, passing around your neck, before coming back to the inside border of the other triangle. To ensure it would maintain the breasts you still don’t have, instead of just covering them as long as you don’t bend your back or go in the water, there is a smaller black cord, albeit still a bit larger than necessary, sewed to the bottom of both triangle, and need to be tied in the back, which you are currently doing.
As soon as you finished the knot, your body change in a flash. (Not that you’re aware of it.) No slow transformation that cause indescribable pleasures or unfathomable pain. One second you’re a rather average man, the next you’re a strong but no less sexy tomboy with black hairs in a seemingly messy pixie haircut, blue eyes one could drown in, and a smile which, combined with your sheer-confidence, make anyone looking at you instantly fall in love. Sure, your breasts are only a C-cup but, you don’t need them bigger. (Bigger boobs wouldn’t look good with your build anyway.)
As you exit your cabin, you fail to notice the man devastated to see you wear the swimsuit he had specially conceived and enchanted to turn himself into the woman he dream of being.