On November 15, 2012, Tanaka entered a tournament to determine the inaugural NEVER Openweight Champion. After wins over Kushida, Taishi Takizawa and Tomohiro Ishii, Tanaka defeated Karl Anderson in the finals of the tournament on November 19 to become the inaugural NEVER Openweight Champion. Tanaka made his first successful title defense on January 4, 2013, at Wrestle Kingdom 7 in Tokyo Dome, where he defeated Shelton Benjamin. Tanaka's second successful title defense took place on February 3, when he defeated Chaos stablemate Tomohiro Ishii. On May 3 at Wrestling Dontaku 2013, Tanaka made his third successful title defense against Tomoaki Honma. On July 20, Tanaka made his fourth successful title defense against Tetsuya Naito. On September 29 at Destruction, Tanaka lost the NEVER Openweight Championship in a rematch with Naito, ending his reign at 314 days.