After continuing to perform as a freelancer for NJPW after 2016 (including as Tiger Mask W, the protagonist of the anime of the same name, from 2016 to 2017), he signed a new full-time contract with NJPW in early 2019, winning the IWGP Heavyweight Championship for the first and only time in his career in 2021 before unifying it with the IWGP Intercontinental Championship to become the inaugural IWGP World Heavyweight Champion later that year.