In April 2017, Tsuji was signed to New Japan Pro-Wrestling (NJPW) under New Japan's "young lion" system.[2][3] A year later, Tsuji as well as fellow young lion, Yuya Uemura, made their pro-wrestling debuts at Lion's Gate Project 11 where Tsuji was defeated by Tomoyuki Oka.[4][5][6] In his second match, he was defeated by Ren Narita.[7] During night one of Wrestling Dontaku 2018, Tsuji and Shota Umino were defeated by Bullet Club (Chase Owens and Yujiro Takahashi).[8]AtLion's Gate Project 12, Tsuji and Uemura went to a time-limit draw.[9]AtLion's Gate Project 13, Tsuji and Uemura wrestled to a draw.[10] On September 5, at Aichi, Tsuji teamed with Narita to defeat Uemura and Umino, winning for the first time. After three years, New Japan reported that Tsuji would be going on overseas excursion along with Uemura as of August 1, 2021. On that day, Tsuji wrestled his last match as a young lion, facing Tetsuya Naito, with whom he had a minor feud with, in a losing effort.
It was announced by Revolution Pro Wrestling (RPW) that Tsuji would make his debut for the promotion on September 4. Tsuji wrestled his first match overseas in a losing effort against Kyle Fletcher.
In July, Tsuji made his debut in the annual G1 Climax tournament, competing in the A Block.[16] Tsuji finished the tournament with 7 points, narrowly missing out on qualifying to advance to the quarter-final round.[17] On August 13, Tsuji pinned reigning IWGP United Kingdom Heavyweight ChampionWill Ospreay in an eight-man tag team match, leading Tsuji to held the IWGP United Kingdom Championship over the fallen Ospreay, setting up at title match at Destruction on September 24, which Tsuji failed to win the title from Ospreay.[18] In October, Tsuji returned to the UK at Royal Quest III, defeating Luke Jacobs.[19] The following month, Tsuji participated in the World Tag League, teaming with Zandokan Jr. of CMLL. The duo finished with 6 points, failing to advance to the semi-finals.[20] Following the tournament, Tsuji renewed a feud with former Young Lion dojo stablemate Yuya Uemura, who had joined Just 5 Guys, which started after Uemura pinned Tsuji in a tag-team match. Due to this, a singles match at Wrestle Kingdom 18 was set.[21] On January 4, 2024 at Wrestle Kingdom, Tsuji was defeated by Uemura.[22]
Tsuji and Uemura continued their feud further into the new year. This culminated on February 24, at The New Beginning in Sapporo, where Tsuji defeated Uemura in a Hair vs. Hair match, forcing Uemura to shave his hair.[23] Tsuji attempted to use his momentum, by entering the New Japan Cup, the following month.[24] Tsuji defeated Jeff Cobb, El Phantasmo and Ren Narita, in the first 3 rounds.[25] In the semi-finals, he defeated Evil, to advance to the tournament finals.[26] In the New Japan Cup final, Tsuji defeated three-time cup winner, Hirooki Goto, to win the 2024 New Japan Cup, his first major accolade in NJPW. After the match, Tsuji claimed he was the face of a new era in NJPW, before being joined in the ring by LIJ leader and stablemate, Tetsuya Naito. Tsuji's New Japan Cup win has earned him a shot at Naito's IWGP World Heavyweight Championship at Sakura Genesis, on April 6.[27] At Sakura Genesis, Tsuji was defeated by Naito.
Tsuji has a twin brother named Shota, who appeared during the final block A of 2023 G1 Climax disguising himself as Yota to bait Gabriel Kidd during his entrance.[28] Shota is a professional stuntman.[29]
