Boredom happened, so I read this. Maybe I'm expecting to much from a perverse loli comedy, but the rules don't seem very consistent. Is it the dream power that keeps her form, or is it the panties? How long is swim class anyway? She went at least a while without panties before transforming before, so she probably could have worn the school swimsuit. Would it work to have panties under the swimsuit? If she can't go back to her male body, then what's with the incomplete transformation in chapter 4? Moreover, does she not generate dream power herself, given that she is, in fact, wearing panties? What happens when she grows up?
That I'm asking this many questions might mean I'm a pedantophile.