Amazon Planet 3: Master and Slave - Amazon Planet

Maggie Kennedy's life changed forever the day she woke up on an alien planet, and learned she was to be trained a sex slave by the Amazons, a race of beings who look like seven-foot-tall beautiful human women... with one notable anatomical difference. Her training is nearing its end, as she comes to learn more and more about why the planet which she now calls home is in danger. It turns out that Maggie is the one of the best sex slaves the Amazons have ever seen, and Maggie at last learns who will be her master. In the meantime she meets fellow slave-in-training Cassidy Gardner, and...
"helps" her along, with her own training... This story is part three in a series. The first five parts are available in a single anthology.  Warning: this 5, 000 word story contains consensual lesbian and futanari sexual situations, and one brief scene with bdsm themes.