[4][5] Through a personal friend's suggestion, Yamanaka initially took on mixed martial arts for health and fitness purposes only.
[6] Her next fight was in the Super Gals Mix Cup Open Weight Tournament 1st Round against Rie Murakami, whom Yamanaka defeated by unanimous decision on November 29, 2006 (2006-11-29) at Smackgirl: Legend of Extreme Women.
[18] On May 16, 2009 (2009-05-16), Yamanaka defeated Josh Barnett's student Shannon Hooper by unanimous decision during the event Jewels 3rd Ring.
[40] On January 6, 2012, the bout's result was changed to a no decision due to Cyborg having tested positive for anabolic steroids.
[41] Yamanaka faced Germaine de Randamie at Strikeforce: Rousey vs. Kaufman on August 18, 2012 (2012-08-18) in San Diego, California.
[49] Yamanaka made her debut in submission wrestling in the 2006 Smackgirl Grappling Queen Tournament, being defeated by American fighter Roxanne Modafferi by decision.
[50][51] She fought two more times on August 31, 2008 (2008-08-31) at Gi grappling 2008, first winning against Akiko Naito and then losing against Sayaka Shioda.
She faced Mayumi "Super Benkei" Aoki, whom Yamanaka had previously defeated in MMA, and won the fight by TKO in round one.