I decided I can't leave Anna as a 20 years old woman. No matter how gorgeous she looks, I could get a lot of troubles because of that. So, I carefully sneaked back in her room and use the regression spell to turn her into a 5 year old girl.
I cannot say it wasn't interesting to watch her turning back to her original age, but I was pretty disappointed that I have lost the chance to be very close to a bombshell like her. I even can feel my dick getting soft while I watched her breast deflating. Every curve that she had gotten with age turning into nothing but the plain body of a very young girl.
Then I realized, I still have the book of time, so I just need to keep practicing until I'm strong enough to get her back and even doing something way more interesting than just watching her. I eagerly went to sleep with the idea of using my new magic skill again.