No one has read a page and it's already the biggest book of the year, but, when you're the author of one of the biggest literary phenomenons of the last 20 years, that's to be expected. Of course, we're talking about J.K. Rowling.

The "Harry Potter" writer's first novel for adults - "The Casual Vacancy" is set to hit bookstores Thursday, and Rowling is making no excuses for the reportedly very grownup prose and plotline. The contents of the 512-page book - already No. 3 on the Amazon best-seller list based on preorders - has been guarded more fiercely than Harry Potter's virginity.

Though some may appear online sooner, reviews of the book by many publications have been embargoed by the publisher until 1am EST on Thursday morning. New Yorker writer Ian Parker was apparently forced to sign a non-disclosure agreement that initially barred him from even taking notes while reading "Vacancy" in the publisher Little, Brown's office.

While little has leaked about the book's contents, Rowling has let fans know "Casual Vacancy" will be quite a departure from her "Harry Potter" novels, and that she considers it her first true adult novel.

"I truly didn't sit down and think, right, now it's time to prove I can... I don't think I physically could write a novel for that reason," Said Rowling to The Guardian. "I just needed to write this book. I like it a lot, I'm proud of it, and that counts for me."

Rowling - who launched the Potter series in 1997 while she was living on welfare and is now worth $900 million - said she considered publishing her latest work anonymously or under a pseudonym, but knew her cover would be blown.

"In some ways I think it's braver to do it like this. And, to an extent, you know what? The worst that can happen is that everyone says, 'Well, that was dreadful, she should have stuck to writing for kids' and I can take that. So, yeah, I'll put it out there, and if everyone says, 'Well, that's shockingly bad - back to wizards with you', then obviously I won't be throwing a party. But I will live. I will live."

Rowling has shrugged off suggestions that she will face criticism for exposing fans of her G-rated readers to the special kind of novel that likens a used condom to "the gossamer cocoon of some huge grub."

Rowling views "Casual Vacancy" as a "comic tragedy" about class warfare in an English village. One passage reads, "The leathery skin of her upper cleavage radiated little cracks that no longer vanished when decompressed."

Another refers to a boy on a school bus "with an ache in his heart and in his balls." There's even a "miraculously unguarded vagina."

Clearly, if E.L. James isn't taking notes, she should start.

"There are certain things you just don't do in fantasy. You don't have sex near unicorns. It's an ironclad rule. It's tacky," Rowling said. "It's not that I just wanted to write about people having sex."

Rowling portrays many of the teens in her new novel as troubled, one is even the mother of a heroin addict. "I had a lot of real-world material in me," the 47-year-old Rowling said of moving beyond fantasy writing.

"There is no part of me that feels that I represented myself as your children's baby-sitter or their teacher," Rowling told the New Yorker magazine. "I was always, I think, completely honest. I'm a writer, and I will write what I want to write."

Rowling has already written a couple of chapters of her next book for adults and is also working on two books for kids too young for Harry Potter.