Good thing I haven't pre-ordered Hayate x Blade volumes 3 and 4 or Sand Chronicles volume 5 yet. I often buy my English manga online at Amazon, but after reading about their systematic, completely senseless and random removal of lgbt titles from their sales rankings (The Lesbian Parenting Book is too "adult", but Playboy: The Complete Centerfolds and Hitler's Mein Kampf aren't?), I'm taking all of my business elsewhere. Sayonara, Amazon. As an extra note, however, Amazon Japan doesn't seem to be enforcing this ridiculous policy, only, as far as I know, Amazon U.S. and Amazon U.K.
Here are two links further elaborating on Amazon's policy at Afterellen and Okazu.
Update 1: When I typed in "homosexuality" in the Amazon search engine under the "Books" category (following up on a comment someone posted under the Afterellen article), the top book that popped up was A Parent's Guide to Preventing Homosexuality. Way to go, Amazon. Here's a link to a petition against Amazon's ranking policy. You can also protest this policy by contacting the Amazon Executive customer service email at email@example.com, calling the customer service phone number: 1-800-201-7575, or logging in to your Amazon account if you have one and visiting: https://www.amazon.com/gp/help/contact-us/general-questions.html?ie=UTF8&browse_node_id=468496
Update 2: One thing that I hadn't considered while writing this post initially was how boycotting Amazon could wind up punishing the authors and publishers who market lgbt titles through Amazon more than Amazon itself, and give Amazon more justification for marginalizing lgbt-inclusive/themed books, movies, etc. The idea of them making any money from a book, manga, or DVD I buy after their "glitch" still annoys me (ask any of my friends- especially from middle school and high school- and they'll testify that I'm a pretty stubbornly vindictive person when somebody knowingly antagonizes me), but I guess that eternally swearing off Amazon isn't the way to go either. Still, they had darn well better fix that glitch soon and who ever is responsible should properly apologize publicly (I know, not going to happen). This whole episode would be more palatable if Amazon would quit using that flimsy "glitch" excuse.