So, what happened near the end? After Natsuru transforms, is that just some random extra screwing him/her, or is it his male form? At any rate, good doujin. And I appreciate the Mikoto pin-up at the end, the poor thing's so frequently overlooked.
Basically, Kaede tries to "excite" Natsuru to the point he will turn to a girl from the orgasm so she can go lesbo on him. Either way, we win because any doujin where a lesbian gets straightened out for a bit is a fun sight.