When Professor Collin Bilsworth suddenly sent out an email letting everyone know he was going on sabbatical, no one particularly cared. The stodgy old man had to be nearing retirement anyways, given his seventy-plus years, and he wasn't particularly liked at the university. A perpetual bachelor and history professor he was obsessed with witchcraft to the point that no one much respected him either. He'd just found some stupid old book in some archive somewhere and had been going on and on about how it was going to make him famous, so they all guessed he was taking a break to focus on studying that.
What was more surprising to everyone was when he announced in the same email that he'd also taken on a new student, a young woman named Callie. Professor Bilsworth hadn't taken on a student in years, and female student in much longer.
What none of them knew was that Callie was actually Professor Bilsworth. The book he'd been so excited about was an actual spellbook, and he'd been thrilled to try it. Collin found a spell to make himself young again and he cast it without a second thought. The spell made him younger sure, shedding more than half a century off his age and leaving him an not-quite-twenty teenager. Unfortunately though it didn't just make him younger. He hadn't realize it was a spellbook for witches, not warlocks. When he cast the spell, it made his gender fit the book's target audience. He was young again, but also a woman.
Collin's ruse with the sabbatical would keep people from asking questions about his sudden disappearance while he did more research and tried to find a way to restore his original sex. He'd saved some money so he'd be good on that front, but he needed an excuse to hang around the university and its libraries. That's why he'd proclaimed himself his own student, pretending to be Callie.
All that had turned out to be easy. What Collin wasn't prepared for was just how horny his new body was. Collin had been a bit of a letch, and he turned himself on everytime he looked down or into a mirror. Once he got himself worked up, he found he couldn't calm himself down until he satisfied those urges.
Soon manual masturbation wasn't enough, and he'd been a bit embarassed when he'd bought a dildo. He'd been more embarassed when he saw it and found himself so entranced by the synthetic male form, he kissed it.
Then of course, he fucked it. He came harder than ever before as it stretched his pussy and he bounced up and down on it, squeezing his tits.
But his young body wasn't satisfied by that for long. More and more he fucked himself with his dildo and found himself imagining it was the real thing. It wasn't long until he finally gave in and let a guy fuck him.
Getting fucked was so fucking incredible, 'Callie' didn't even mind when the guy finished by fucking her tits and cumming all over her face.
Professor Bilsworth never did return from sabbatical, but his young student Callie got a well-earned reputation as one of the biggest sluts on campus.
Collin was thrilled to be young again. And to be a young woman turned out to be even better.