Douki

Tatsuya Hayama (葉山 達也), better known by his ring name Douki (stylised in all caps as DOUKI), is a Japanese professional wrestler currently signed to New Japan Pro-Wrestling (NJPW), where he is a member of the Just 5 Guys stable and the current IWGP Junior Heavyweight Champion in his first reign. Douki was a part of the Suzuki-gun stable from 2019 till the faction's disbandment in 2022.

Early career
In May 2010, Hayama had planned to go to Mexico by himself, but Milano Collection A.T. had introduced him to Taichi. After that, he went to CMLL's wrestling school every day and practiced at the gym with Taichi, and debuted under the name Kansuke in November of the same year.

In 2012, when he joined Los Perros del Mal (a stable that was formed in December 2008), Hayama thought, "There are other Japanese wrestlers, so let's change the character." He thus adopted the ring name Douki. He served as a member of the stable Japones del Mal. His ring name is derived from Kansuke Yamamoto's ordination name "Michiki".

After spending time in Mexico, Douki made his first appearance in Japan at a Tokyo Gurentai show on October 10, 2015.

Suzuki-gun (2019–2022)
On May 10, 2019, El Desperado had to be pulled from the Best of the Super Juniors Tournament due to injury, and Taichi introduced Douki as Suzuki-gun's newest member to replace Desperado. Douki would finish with only 2 points in the tournament.

On August 1, 2020, NJPW announced a tournament to crown new NEVER Openweight 6-Man Tag Team Champions in which Douki took part alongside stablemates Minoru Suzuki and El Desperado.

In March 2022, Douki participated in the New Japan Cup, where he lost to fellow Suzuki-gun stablemate Zack Sabre Jr. in the second round. In November, Douki and Yoshinobu Kanemaru competed in the Super Junior Tag League, finishing with eight points and failing to advance to the finals.

In December, at the World Tag League and Best of the Super Juniors finals, Minoru Suzuki announced the disbandment of Suzuki-gun by the end of the year. The final match between the faction took place on December 23, where the team of Taichi, Sabre Jr, Kanemaru and Douki defeated Suzuki, Lance Archer, Desperado and Michinoku. After the match, each of the Suzuki-gun members spoke about their memories as a part of the group and thanked leader Suzuki. The night ended with all members posing with the Suzuki-gun flag, only to be interrupted by former member Takashi Iizuka, causing all nine men to pose in the ring, behind the Suzuki-gun flag.

Just 5 Guys (2023–present)
On January 5, 2023, at New Year Dash, Michinoku, Taichi, Douki, and Kanemaru formed Just 4 Guys with the aim of reaching the top of New Japan. On February 4, at The New Beginning in Sapporo, Douki and Yoshinobu Kanemaru challenged Catch 2/2 (Francesco Akira and TJP) for the IWGP Junior Heavyweight Tag Team Championship, but lost. In the quarterfinal round of the New Japan Cup, Sanada defeated LIJ stablemate and leader, Tetsuya Naito. After the match, Sanada was joined in the ring by Taichi, Kanemaru, Michinoku and Douki, where they all shook hands, thus joining the stable which changed their name to Just 5 Guys. Through NJPW's partnership with All Elite Wrestling (AEW), Douki made his AEW debut on the June 23 episode of AEW Rampage, losing to "Jungle Boy" Jack Perry. On June 25 at Forbidden Door, Douki accompanied Sanada for the latter's successful IWGP world title defense against Perry. At the July 5, 2024 New Japan Soul event, Douki defeated El Desperado to capture his first championship, becoming the IWGP Junior Heavyweight Champion.

Championships and accomplishments

 * New Japan Pro-Wrestling
 * IWGP Junior Heavyweight Championship (1 time, current)