IWGPジュニアヘビー級王座
On February 25, 2011, it was announced that Kushida, with Tajiri's blessing, would be leaving Smash and becoming a full-time member of the New Japan roster, beginning on April 1. On March 19 Kushida unsuccessfully challenged Prince Devitt for the IWGP Junior Heavyweight Championship. On May 26, Kushida entered the 2011 Best of the Super Juniors tournament. After winning five out of his eight-round robin stage matches, he finished fourth out of the nine wrestlers in his block, narrowly missing the semifinals of the tournament. Kushida then went on to compete in J Sports Crown Openweight 6 Man Tag Tournament 2011 with Hiroshi Tanahashi and Máscara Dorada, however the trio were beaten in the second round by Jyushin Thunder Liger, Karl Anderson and Giant Bernard. On August 27, 2011, he participated in the Destroyer Cup, a special battle royal at All Together. On September 19, Kushida was set to challenge Kota Ibushi for the IWGP Junior Heavyweight Championship, but a week earlier, Ibushi was forced to pull out of the match and vacate the title, after dislocating his left shoulder. Kushida was then booked in a decision match against former champion Prince Devitt to determine a new champion. On September 19, Kushida was defeated by Prince Devitt in a match for the vacant IWGP Junior Heavyweight Championship. On November 12 at Power Struggle, Kushida and Tiger Mask unsuccessfully challenged Davey Richards and Rocky Romero for the IWGP Junior Heavyweight Tag Team Championship.