Bonsai Jiu-jitsu club competitor, submission specialist. His favorite technique is
Triangle choke. A holder of a black belt
Brazilian jiu-jitsu from the city of
Iwata. In 2008–2014 he fought mainly at Japanese galas
DEEP and
Rings, beating at that time, among others of the former
Shooto champion of
Hideki Kadowaka.
Konfrontacja Sztuk Walki At the
KSW 30: Genesis defeated Anzor Azhiev by triangle choke in the 1st round. He was also awarded the
Submission of the Night bonus award. After a successful debut for the KSW, he took part in a featherweight tournament organized by the Chinese federation Rebel FC, which won and became a champion, defeating the American
Miguel Torres. At
KSW 33: Materla vs. Khalidov, which took place on November 28, 2015, fought a duel with
Artur Sowiński for the inaugural
KSW Featherweight Championship, eventually losing by the judges' decision. Both were awarded the
Fight of the Night bonus award. After another stint returning to Asia, picking two third round submission wins at Pancrase 277 and Rebel FC 4, Kleber returned to KSW, facing Leszek Krakowski on October 1, 2016, at
KSW 36. He won the bout via triangle choke in the first round. He was awarded the
Submission of the Night bonus award.
Featherweight championship and loss of the title On May 27, 2017, at the
KSW 39 held at the
Stadion Narodowy, he won the
KSW Featherweight Championship, defeating then featherweight champion Marcin Wrzosek via unanimous decision. Kleber was to defend his title against
Artur Sowiński at
KSW 41 on December 23, 2017. However, after missing weight, Erbst was stripped of the belt, meaning only Sowiński was eligible for the title. Erbst won the bout via rear-naked choke in the third round. Kleber was scheduled to rematch Marcin Wrzosek for the vacant featherweight title on June 9, 2018, at
KSW 44. However Wrzosek suffered a pectoral muscle tear and was forced out of the rematch. As a result, Marian Ziółkowski stepped in against Erbst in a catchweight fight. Erbst won the bout via armbar in the first round. He was awarded the
Submission of the Month bonus award. Kleber faced
Mateusz Gamrot on December 1, 2018, at
KSW 46: Narkun vs. Khalidov 2. He lost the bout via a unanimous decision.
Rizin Fighting Federation After a first round submission win at ONE Japan Series against
Akiyo Nishiura, Kleber made his Rizin debut on December 31, 2020, at during
Rizin 26 against Kyle Aguon He won the bout via brabo choke in the first round. Kleber faced Kazumasa Majima at
Rizin 27 on March 21, 2021. He won via triangle choke in the second round. Kleber faced
Mikuru Asakura at
Rizin 28. He won the bout after choking Mikuru unconscious via triangle choke. Kleber headlined
Rizin Trigger 2 on February 23, 2022, against
Ulka Sasaki. After overcoming a knockdown in the first round, Kleber submitted Sasaki in the second round via rear-naked choke. Kleber faced Kyohei Hagiwara on May 5, 2022, in the main event of
Rizin Landmark 3. He won the bout in the first round with a face crank.
Rizin FF Featherweight championship On October 23, 2022, Kleber faced reigning champion Juntaro Ushiku for the
Rizin Featherweight Championship at
Rizin 39. taking control in the first round with a tackle takedown, and in the second round, he threw him down with a hip throw and set up a triangle choke to win by triangle choke to win the title. Kleber faced reigning
Bellator Featherweight Champion Patrício Pitbull in a non-title bout at
Bellator MMA vs. Rizin on December 31, 2022. He lost the bout by unanimous decision.
Rizin title stripped Kleber was set to make his first title defense against
Chihiro Suzuki on June 24, 2023, at
Rizin 43. At the weigh-ins, Kleber weighed in at 145.88 pounds, 0.88 pounds over the divisional title limit. As a result, upon commencement of the fight, Kleber was officially stripped of the championship, and only Suzuki is eligible to win the title. Although Kleber submitted Suzuki via triangle choke at the 2:59 minute mark of the opening round, the fight result was immediately overturned into a no-contest, due to Kleber's weight miss. Koike Erbst faced
Masanori Kanehara at
Rizin 44 on September 24, 2023. He lost the bout via unanimous decision, having his BJJ skills be nullified by Kanehara's wrestling acumen. Koike Erbst faced Yutaka Saito on December 31, 2023, at
Rizin 45, and won the bout via brabo choke in the third round. Koike Erbst next faced former
Bellator and
Rizin Bantamweight champion
Juan Archuleta at
Rizin 47 on June 9, 2024. He won the fight via an inverted heel hook submission in the first round.
Regaining Rizin FF Featherweight championship Koike Erbst faced
Chihiro Suzuki in a rematch for the
Rizin Featherweight Championship at
Rizin 49 on December 31, 2024. He won the bout via unanimous decision. Koike Erbst faced
Razhabali Shaydullaev for the Rizin featherweight title on May 4, 2025, at
Rizin: Otoko Matsuri. He lost the title by knockout in the first round. == Championships and accomplishments ==