UFC champion Ronda Rousey is releasing her autobiography, "My Fight/Your Fight," in May, but already the book is causing controversy.

A photo posted by rondarousey (@rondarousey) on Apr 8, 2015 at 10:59am PDT

The book is available for purchase on Wal-Mart's website, but it won't be sold in stores because the retail giant claims the content is too violent, reports The New York Post.

Wal-Mart spokesperson Danit Marquardt told Business Insider, "There are a variety of factors that we look at when determining what items to offer our customers. At this point, we've chosen to offer this particular title to our customers online."

The news has caused UFC and MMA fans to point out Wal-Mart sold "American Sniper" in stores, sells guns in certain states and violent video games.

On Wednesday, Rousey took to Instagram to confront Wal-Mart's decision.

"'Success is the best revenge' one of many lessons I learned from fighting that helped me fight through life's battles off the mat and outside the octagon. @walmart is welcome to watch the success of this publication from the sidelines if they choose," she wrote.

Marquardt told Business Insider, "We will continue to watch how customers respond," regarding the Rousey book situation. She added that, "Across all of our merchandise categories, we sell an abbreviated assortment in stores when compared to our ecommerce site."

According to Amazon, the summary of "My Fight/Your Fight" reads as follows: "In this revealing memoir, undefeated UFC champion and Hollywood star Ronda Rousey charts her difficult path to glory, revealing her tragic childhood and her father's suicide, her meteoric rise to fame, the secret behind her undefeated UFC record, and what it takes to become the toughest woman on Earth."

The "toughest woman on Earth" has also found success as an actress outside of the ring. Her film debut was in the all-star 2014 action movie "The Expendables 3." She appears in "Fast and Furious 7," which is in theaters currently. She plays Kara, a fearsome villain who goes out of her way to stop the heroes from interfering with Deckard Shaw's evil plans. In the film, she fights Letty, played by Michelle Rodriguez.

Watch for Rousey in the movie "Entourage" being released June 5 in U.S. theaters.