Tetsuya Naito
On January 4, 2021, at Wrestle Kingdom 15, Ibushi pinned Tetsuya Naito in the main event to win the IWGP Heavyweight and Intercontinental Championships, becoming the second man to ever win the IWGP Heavyweight and Junior Heavyweight Championships in history (first being Nobuhiko Takada). He went on to successfully defend both titles against Jay White the following night on Wrestle Kingdom 15 Night 2. Ibushi would later declare his intentions to unify the IWGP Heavyweight and Intercontinental Championships.