L'Anima Gemella is a movie that features some body swapping/f2f transformation, though the process is unseen. The sexiness of the main actress more than makes up for it, though. The link below is to a part right after a girl turns into the girl she's jealous of. The story is best described in the video description.
Part 6
Unfortunately, Part 5 must have been removed. It shows her waking up in the tub and checking herself out a little more.