Wasn't really sure where to put this, so this seems like the appropriate place. Sorry if this has already been posted before, but the search system doesn't like 123 as part of a search string.
http://www.onemanga.com/Change_123/
The basic story is that a girl named Motoko has Dissociative Identity Disorder brought on by the hellish martial arts training that her three fathers put her through. As a result, her mind fractured somewhat, giving rise to Hibiki, Fujito, and Mikiri, three totally separate people living inside the body of a very shy girl.
Now, the reason I'm posting this is that whenever one of her other personalities takes over, her body physically changes. Hibiki is very tomboyish in appearance, Fujito appears to be a little taller and skinnier than Motoko, and Mikiri has larger breasts than any other personality to the point that she actually destroys a few bras when the appears.
There isn't really very much process aside from some early BE on the part of Mikiri, but it's definitely something new. Just figured some might like to check it out.