A Girl Corrupted by the Internet is the Summoned Hero?! by Eliezer Yudkowsky
My rating: 5 of 5 stars
The intersection of decision theory and sexual depravity is not my usual go-to place for light reading, but in this case the combination works beautifully.
Although the book is woefully short, the author has managed to set up a rational hard fantasy premise that successfully thrusts the reader from beginning to climax. (Puns intended.)
The book will be more enjoyable if you have some familiarity with Japanese light novels, tropes concerning B theory time travel paradoxes (or, more specifically, consistency re: decision theory), and ...advanced... pornography. But it's readable even without these prerequisites.
I'm giving it five stars because it was really good; but at the same time I'm quite disappointed at the extremely short length. I feel teased by how short it lasted!
View all my reviews