"Now for your 'Transform', you will become in my sexual fantasy once a week. Plus, when you transform, your entire body changes physically and mentally to match your new appearance. And I want to see your transformation slowly. After the end of a week, you will change back on Sunday and change again after Monday." you answered.
"Oh, that's interesting, hun." your girlfriend smiles. "I didn't know could think of that idea. Anyway, what's your sexual fantasy I'm gotta be, hun?"
"Well, I... I don't know, babe. I just don't know how to say," you awkwardly reply as it's hard to answer the question.
"Aww, don't be like that, silly. I know what is your dirty secrets, hun," she responds with suspicious eye contact and a smile. "I know you have a lot of things in your head since we did our erotic role-playing game. C'mon, you don't need to hide, hun."
"Well, okay fine. I got me, babe," you said with a disappointed face, but you still smile with your girlfriend. "But I'll tell you when you change into my dream girl."
With that, you look at your girlfriend as your girlfriend's skin starts to shift strangely.