Demon's gifts

Sorta a story idea I'm working on. anyone care to suggest any ideas?

Basic cliche parts of it:

1. Girl is unsatisfied with body

2. She and her room-mate preform a spell turning her into a special demon girl.

3. through a certain method she expands her figure.

4. she is allowed to keep her powers and can transform into demon form at will.

5. She is given a watchdog though.

6. is a several part series.

anyone care to suggest on how I can improve it. if they care at all.