Kleber Koike Erbst (クレベル・コイケ・エルベスト, Kureberu Koike Erubesuto, born October 16, 1989) is a Brazilian-born Japanese mixed martial artist who competes in the Featherweight division of Rizin Fighting Federation, where he is the current Rizin Featherweight Champion.

[2] Born in São Paulo, Brazil, to a Brazilian father of German, Portuguese and Japanese descent and a Japanese mother, Kleber lived in Brazil in his teenage years, until financial troubles led his parents to move to Japan.

Initially intending to help his parents and return to Brazil, but once he met jiu-jitsu, he decided to stay in Japan.

When financial crisis hit Japan, his parents decided to move back to Brazil, leaving behind an 18 years old Erbst who wanted to stay.

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.

[6] 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.

[15] Kleber was scheduled to rematch Marcin Wrzosek for the vacant featherweight title on June 9, 2018, at KSW 44.

[37][38] Kleber was set to make his first title defense against Chihiro Suzuki on June 24, 2023, at Rizin 43.

As a result, upon commencement of the fight, Kleber was officially stripped of the championship, and only Suzuki is eligible to win the title.

[42] He lost the bout via unanimous decision, having his BJJ skills be nullified by Kanehara's wrestling acumen.

[43] Koike Erbst faced Yutaka Saito on December 31, 2023, at Rizin 45,[44] and won the bout via brabo choke in the third round.