On June 7, 2015, Kushida defeated Kyle O'Reilly in the finals to win the 2015 Best of the Super Juniors and earn a shot at the IWGP Junior Heavyweight Championship.
On July 5 at Dominion 7.5 in Osaka-jo Hall, Kushida defeated Kenny Omega to win the IWGP Junior Heavyweight Championship for the second time.
He made his first successful title defense on August 16 against the winner of the 2014 Best of the Super Juniors, Ricochet.
On August 21, Kushida returned to ROH, losing to Matt Sydal in a non-title match, after which he agreed to defend his title against Sydal.
On September 23 at Destruction in Okayama, Kushida lost the title back to Kenny Omega.
Four days later at Destruction in Kobe, Kushida and the returning Alex Shelley unsuccessfully challenged reDRagon for the IWGP Junior Heavyweight Tag Team Championship.
On January 4, 2016, at Wrestle Kingdom 10 in Tokyo Dome, Kushida defeated Kenny Omega to regain the IWGP Junior Heavyweight Championship.
He made his first successful title defense on February 14 at The New Beginning in Niigata against Bushi.
Kushida's second title defense took place on March 12 at an ROH event in Philadelphia, where he defeated ACH.
On April 10 at Invasion Attack 2016, Kushida defeated the debuting Will Ospreay for his third successful defense.
His fourth defense took place on May 3 at Wrestling Dontaku 2016, where he defeated veteran wrestler Jyushin Thunder Liger.
Later in the month, Kushida entered the 2016 Best of the Super Juniors.
Finishing with a record of four wins and three losses, he was eliminated from the tournament after losing to Bushi in his final round-robin match.
On June 19 at Dominion 6.19 in Osaka-jo Hall, Kushida defeated Best of the Super Juniors winner Will Ospreay for his fifth successful title defense.
On July 20, Kushida entered the 2016 Super J-Cup tournament, defeating Pro Wrestling Noah representative Taiji Ishimori in his first round match.
On August 21, Kushida first defeated another Noah representative, Kenoh, in the second round and then two Suzuki-gun representatives, Taichi and Yoshinobu Kanemaru, in the semifinals and finals, respectively, to win the 2016 Super J-Cup.

On September 17 at Destruction in Tokyo, Kushida lost the IWGP Junior Heavyweight Championship to Bushi.
Kushida regained the title from Bushi on November 5 at Power Struggle.
He lost the title to Hiromu Takahashi on January 4, 2017, at Wrestle Kingdom 11 in Tokyo Dome.
Kushida received his title rematch against Takahashi on April 9 at Sakura Genesis 2017, but was defeated in less than two minutes.
The following month, Kushida took part in the NJPW and ROH co-produced War of the Worlds tour.
On the final night of the tour, May 14, Kushida defeated Marty Scurll to become the new ROH World Television Champion.
Upon his return to Japan, Kushida entered the 2017 Best of the Super Juniors, where he won his block with a record of four wins and three losses, advancing to the finals.
On June 3, Kushida defeated Will Ospreay in the finals to win his second Best of the Super Juniors.
On June 11 at Dominion 6.11 in Osaka-jo Hall, Kushida defeated Hiromu Takahashi to win the IWGP Junior Heavyweight Championship for the fifth time.
On September 22, Kushida returned to ROH at Death Before Dishonor XV, where he lost the ROH World Television Championship to Kenny King.
On October 9 at King of Pro-Wrestling, Kushida lost the IWGP Junior Heavyweight Championship to Will Ospreay.
At Wrestle Kingdom on January 4, 2018, he failed to regain the title from Marty Scurll in a four-way match that also included Hiromu Takahashi and Will Ospreay, who won the championship by pinning Scurll.
Kushida got another rematch for the title on May 4 at Wrestling Dontaku, but was again defeated by Ospreay.
Later that month, he entered the 2018 Best of the Super Juniors tournament.
He finished the tournament with 4 wins and 3 losses, failing to advance to the finals.
After the IWGP Junior Heavyweight Championship was vacated when Hiromu Takahashi suffered a neck injury during a successful title defense against Dragon Lee at the G1 Sp
On June 7, 2015, Kushida defeated Kyle O'Reilly in the finals to win the 2015 Best of the Super Juniors and earn a shot at the IWGP Junior Heavyweight Championship. On July 5 at Dominion 7.5 in Osaka-jo Hall, Kushida defeated Kenny Omega to win the IWGP Junior Heavyweight Championship for the second time. He made his first successful title defense on August 16 against the winner of the 2014 Best of the Super Juniors, Ricochet. On August 21, Kushida returned to ROH, losing to Matt Sydal in a non-title match, after which he agreed to defend his title against Sydal. On September 23 at Destruction in Okayama, Kushida lost the title back to Kenny Omega. Four days later at Destruction in Kobe, Kushida and the returning Alex Shelley unsuccessfully challenged reDRagon for the IWGP Junior Heavyweight Tag Team Championship. On January 4, 2016, at Wrestle Kingdom 10 in Tokyo Dome, Kushida defeated Kenny Omega to regain the IWGP Junior Heavyweight Championship. He made his first successful title defense on February 14 at The New Beginning in Niigata against Bushi. Kushida's second title defense took place on March 12 at an ROH event in Philadelphia, where he defeated ACH. On April 10 at Invasion Attack 2016, Kushida defeated the debuting Will Ospreay for his third successful defense. His fourth defense took place on May 3 at Wrestling Dontaku 2016, where he defeated veteran wrestler Jyushin Thunder Liger. Later in the month, Kushida entered the 2016 Best of the Super Juniors. Finishing with a record of four wins and three losses, he was eliminated from the tournament after losing to Bushi in his final round-robin match. On June 19 at Dominion 6.19 in Osaka-jo Hall, Kushida defeated Best of the Super Juniors winner Will Ospreay for his fifth successful title defense. On July 20, Kushida entered the 2016 Super J-Cup tournament, defeating Pro Wrestling Noah representative Taiji Ishimori in his first round match. On August 21, Kushida first defeated another Noah representative, Kenoh, in the second round and then two Suzuki-gun representatives, Taichi and Yoshinobu Kanemaru, in the semifinals and finals, respectively, to win the 2016 Super J-Cup.
On September 17 at Destruction in Tokyo, Kushida lost the IWGP Junior Heavyweight Championship to Bushi. Kushida regained the title from Bushi on November 5 at Power Struggle. He lost the title to Hiromu Takahashi on January 4, 2017, at Wrestle Kingdom 11 in Tokyo Dome. Kushida received his title rematch against Takahashi on April 9 at Sakura Genesis 2017, but was defeated in less than two minutes. The following month, Kushida took part in the NJPW and ROH co-produced War of the Worlds tour. On the final night of the tour, May 14, Kushida defeated Marty Scurll to become the new ROH World Television Champion. Upon his return to Japan, Kushida entered the 2017 Best of the Super Juniors, where he won his block with a record of four wins and three losses, advancing to the finals. On June 3, Kushida defeated Will Ospreay in the finals to win his second Best of the Super Juniors. On June 11 at Dominion 6.11 in Osaka-jo Hall, Kushida defeated Hiromu Takahashi to win the IWGP Junior Heavyweight Championship for the fifth time. On September 22, Kushida returned to ROH at Death Before Dishonor XV, where he lost the ROH World Television Championship to Kenny King. On October 9 at King of Pro-Wrestling, Kushida lost the IWGP Junior Heavyweight Championship to Will Ospreay. At Wrestle Kingdom on January 4, 2018, he failed to regain the title from Marty Scurll in a four-way match that also included Hiromu Takahashi and Will Ospreay, who won the championship by pinning Scurll. Kushida got another rematch for the title on May 4 at Wrestling Dontaku, but was again defeated by Ospreay. Later that month, he entered the 2018 Best of the Super Juniors tournament. He finished the tournament with 4 wins and 3 losses, failing to advance to the finals. After the IWGP Junior Heavyweight Championship was vacated when Hiromu Takahashi suffered a neck injury during a successful title defense against Dragon Lee at the G1 Sp
Yujiro Kushida