NEVER無差別級王座
On October 13 at King of Pro-Wrestling, Ishii regained the NEVER Openweight Championship from Yujiro Takahashi, becoming the first two-time holder of the title. Ishii made his first successful title defense on November 8 at Power Struggle against Hirooki Goto. From November 23 to December 5, Ishii took part in the 2014 World Tag League, alongside Shinsuke Nakamura. The team finished second in their block with a record of four wins and three losses, narrowly missing the finals of the tournament due to losing to Hirooki Goto and Katsuyori Shibata on the final day. On January 4, 2015, at Wrestle Kingdom 9 in Tokyo Dome, Ishii lost the NEVER Openweight Championship to Togi Makabe in his second defense. On February 14 at The New Beginning in Sendai, Ishii defeated Tomoaki Honma, a late replacement for an ill Togi Makabe, to win the now vacant NEVER Openweight Championship for the third time. Ishii once again lost the title to Makabe in his first defense on April 29 at "Wrestling Hinokuni". The two faced off in another title match on July 5 at Dominion 7.5 in Osaka-jo Hall, where Makabe was once again victorious. From July 23 to August 15, Ishii took part in the 2015 G1 Climax, where he finished in the middle of his block with a record of five wins and four losses. On October 12 at King of Pro-Wrestling, Ishii defeated Makabe to win the NEVER Openweight Championship for the fourth time. Ishii made his first successful title defense on November 7 at Power Struggle against Tomoaki Honma. Ishii's reign ended in his next defense, when he was defeated by Katsuyori Shibata on January 4, 2016, at Wrestle Kingdom 10 in Tokyo Dome. Ishii received a rematch for the title on February 11 at The New Beginning in Osaka, but was again defeated by Shibata.