In March, Tanahashi was eliminated from the 2015 New Japan Cup by Toru Yano in less than three minutes, re-igniting the old feud between the two. The rivalry culminated on July 5 at Dominion 7.5 in Osaka-jo Hall, where Tanahashi defeated Yano. From July 20 to August 14, Tanahashi took part in the round-robin stage of the 2015 G1 Climax. He won his block with a record of seven wins and two losses, advancing to the finals. On August 16, Tanahashi defeated Shinsuke Nakamura in the finals to win his second G1 Climax. Tanahashi was handed a contract, which gave him the right to challenge for the IWGP Heavyweight Championship at Wrestle Kingdom 10 in Tokyo Dome, that he would have to defend for the rest of the year. During September and October, Tanahashi successfully defended the contract against Bad Luck Fale and Tetsuya Naito, avenging his two losses suffered during the 2015 G1 Climax. On January 4, 2016, at Wrestle Kingdom 10 in Tokyo Dome, Tanahashi unsuccessfully challenged Kazuchika Okada for the IWGP Heavyweight Championship. The loss ended his Tokyo Dome main event win streak at five. On February 14 at The New Beginning in Niigata, Tanahashi was defeated by Kenny Omega in a match to determine the new IWGP Intercontinental Champion. On March 20, Tanahashi teamed with Juice Robinson and Michael Elgin to unsuccessfully challenge The Elite (Omega and The Young Bucks (Matt Jackson and Nick Jackson)) for the NEVER Openweight 6-Man Tag Team Championship.