Ashley Berry 
Futanari Sex Ed 3 – Extra Credit (Book 3 of "Futanari Sex Ed") [EPUB ebook] 

For their PE essay, Futa teens Zara and Amber must try out five different condom brands…on each other! Meanwhile, Leslie is face-to-face with a futanari roller derby team who can’t get their heads in the game. She knows how to motivate them, promise them a big celebration afterwards in the locker room, where she’s the entertainment!